You may have noticed that recently allocated [dedicated IP addresses](https://www.sparkpost.com/docs/deliverability/managing-dedicated-ip-pools/) in your SparkPost account come from specific address ranges. 

Unless you are using our [Bring your Own IP](https://www.sparkpost.com/docs/tech-resources/bring-your-own-ip/) feature, your dedicated IPs come from a range registered to SparkPost.

```
whois 147.253.215.24
:
NetRange:       147.253.208.0 - 147.253.223.255
CIDR:           147.253.208.0/20
:
Organization:   Sparkpost (MS-820)
:
```

SparkPost automatically provides [Full-circle reverse DNS](https://en.wikipedia.org/wiki/Forward-confirmed_reverse_DNS), otherwise known as _“Forward-confirmed reverse DNS”_, for these dedicated IPs.

The IP address resolves back to a specific hostname using a PTR record, which uniquely resolves forward to that same IP address. You can see this using:

```
dig +short -x 147.253.215.24
mta-215-24.sparkpostmail.com.

dig +short A mta-215-24.sparkpostmail.com
147.253.215.24
```

The lookup from IP address back to hostname is done via a DNS PTR record. You can see this in full using the `dig -x` command above without the `+short` option:

```
dig -x 147.253.215.24

; <<>> DiG 9.10.6 <<>> -x 147.253.215.24
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62812
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;24.215.253.147.in-addr.arpa.	IN	PTR

;; ANSWER SECTION:
24.215.253.147.in-addr.arpa. 296 IN	PTR	mta-215-24.sparkpostmail.com.

;; Query time: 11 msec
;; SERVER: 194.168.4.100#53(194.168.4.100)
;; WHEN: Wed Aug 14 12:19:03 BST 2019
;; MSG SIZE  rcvd: 98
```

You can also use online tools such as [MX Toolbox](https://mxtoolbox.com/ReverseLookup.aspx/) to view this relationship.

## EHLO hostnames in the outbound SMTP conversation
When SparkPost delivers email onwards to a mailbox provider, the SMTP conversation starts with the remote provider announcing themselves, and SparkPost replies with its hostname in the EHLO command, like this. The lines from SparkPost are annotated thus: `>`
```
  220 smtp.proxy.trymsys.net ESMTP Service Ready
> EHLO mta-215-24.sparkpostmail.com
  250-Hello mta-215-24.sparkpostmail.com
  250-PIPELINING
  250-8BITMIME
  250-ENHANCEDSTATUSCODES
  250-STARTTLS
  250 AUTH PLAIN LOGIN
> STARTTLS
  220 2.0.0 Ready to start TLS
```

Here's a network-level message exchange, showing the initial SMTP conversation, captured in WireShark.

![](media/ded-ip-full-circle-dns/wireshark-screenshot.png)


Dedicated IP addresses issued from SparkPost address ranges automatically have Full Circle Reverse DNS

Dedicated IPs - full-circle reverse DNS and EHLO hostnames on SparkPost

Common Billing Errors If you have found your way here you are probably experiencing a problem with either adding or updating your billing information to your Spark Post account and will have seen the following alert in the UI This means that your credit card issuer has declined payment this...

Common Billing Errors

On the dashboard go to Account Billing There you will be able to see the plan you are currently on as well as all of the other plans we provide Once you decide on the plan you would like to upgrade to click on it A window will drop down...

Upgrading Your Account

The Usage Report allows you to easily keep track of how many emails you've sent over the last month day and hour It also displays your sending limits for each time period along with any overages above your monthly limit Note that free accounts are not permitted any overage Attempts...

Usage Report and Account Limits

Billing

Use this topic for all email delivery questions

Bounce Classification Codes Following is a list of bounce classification codes and their meanings Classification Name Description Category 1 Undetermined The response text could not be identified Undetermined 10 Invalid Recipient The recipient is invalid Hard 20 Soft Bounce The message soft bounced Soft 21 DNS Failure The message bounced...

Bounce Classification Codes

Dedicated IP addresses are available for any account with the exception of the FREE plan with no credit card details on file Any new dedicated IP address added to your account will have a neutral initial reputation which means that you will be responsible for properly warming up your new...

Dedicated IP Pools

Get the full picture of your email lifecycle by combining your sending, engagement, and deliverability data into a single view. Deliverability Analytics empowers you to make effective, timely, data-driven, and strategic decisions to maximize the success of your email program.

Deliverability Analytics

You are receiving this error because Gmail uses the return path domain for that error message However it is your from domain that the reputation is actually referencing We have clients sending to Gmail from the same return path and I Ps that are not experiencing inbox issues Steps Towards...

When sending to Gmail subscribers I see this error: "We've found that lots of messages from sparkpostmail.com are spam"

When deploying an email campaign you may notice that the number of recipients injected may not match the number of recipients targeted This is due to suppressions that are applied prior to the actual deployment Your injection list is first bounced against your own suppression list opt outs hard bounces...

Global Suppression List

IP warming is the process of methodically adding email volume to a new IP address gradually over several days and weeks in order to establish a positive sending reputation with mailbox providers. Mailbox providers view email from a new IP address as suspicious until...

IP Warm-up Strategy Overview

So now you have dedicated I Ps In which IP pools would you like them Would you like a marketing pool Would you like a transaction pool You can manage this in the SparkPost app In the SparkPost app select account IP Pools The default pool is already there for...

Managing dedicated IP Pools

In order to get the best deliverability and inbox placement rates you need to establish yourself as a legitimate sender by developing a good reputation with mailbox providers like Gmail and Hotmail Here’s how Permission only email to the people who have subscribed to receive your mail Transparency make sure...

Optimizing Deliverability and Inbox Placement

Unfortunately we do not have the luxury of being assigned large blocks of IP space by our provider and so we cannot use the ip 4 mechanism in our SPF records this has meant we've had to look for more creative approaches ones that require extra DNS queries It would...

SPF and ip4 Mechanisms

If you are experiencing delays or other deliverability issues to your domains hosted by Google Apps please whitelist the Spark Post sending I Ps using the Google documentation https support google com a answer 60751 To find out what Spark Post sending I Ps to whitelist depends on whether you...

Whitelisting SparkPost sending IP addresses with Google Apps

Deliverability

If you have received an email from abuse sparkpost com and sent your reply but never heard back it could be because the email wasn't received for some reason This can sometimes happen if there is a problem with your IP reputation or if perhaps there are bad links in...

Abuse@sparkpost.com is Not Returning My Emails

Q What URL do I use to access the REST AP Is A The REST AP Is can be accessed at https api sparkpost com api v 1 so for example the Transmissions API can be accessed by POS Ting to https api sparkpost com api v 1 transmissions you'll...

How Do I Access the REST APIs?

The older paid plans no longer offer the ability to add dedicated IPs to your account.

Can I add a dedicated IP to my existing Paid plan?

Q I receive a 250 OK when injecting into the system through SMTP but the message shows up as rejected in the reports Why is my message being rejected A The 250 OK response indicates that the connection was properly authenticated and that the message was accepted by Spark Post...

After Receiving a 250 OK, Why Are Messages Being Rejected?

SparkPost supports Transport Layer Security(TLS). TLS is a cryptographic protocol that provides security on the Internet and lets you encrypt emails during transit. All incoming API calls to SparkPost use HTTPS and are SSL/TLS encrypted. SparkPost also offers TLS support for incoming SMTP traffic if the user chooses to enable it.

Are you sending emails as Encrypted messages?

Domain Ownership And Control You can send mail through Spark Post from any domain that you or your customers control By verifying your sending domains with Spark Post you're letting us know that you control them and that you authorize delivery from those domains The SPF and DKIM domain verification...

Can I send from any domain?

When you switch to a new plan (either upgrade or downgrade), you won't be able to later switch back to an old plan that we no longer offer.

Can I switch back to an old plan?

If you no longer wish to use SparkPost, you have two options: (1) downgrade to the free Test plan, or (2) cancel your account...

How Do I Downgrade or Cancel My Account?

SparkPost allows you to designate recipients with the X MSYS API header as cc bcc or archive recipients. SparkPost will generate a unique message for each valid CC BCC and Archive recipient.

What are the differences between CC, BCC, and archive recipients?

Before getting started please read What are the differences between CC BCC and archive recipients Note to use CC BCC and Archiving with SMTP check out our SMTP API reference documentation Note Please be advised that CC and BCC messages count towards your usage What is CC CC is a...

Using CC and BCC with the REST API

Free plans even with Add-ons such as a dedicated IP or previous overages are still subject to the same Free plan support changes

I have paid for overages or have a dedicated IP on my Free plan, how does this affect my support moving forward?

When creating HTML content for email CSS is often an issue Many email clients use HTML themselves so special care is needed to avoid clashing with their page layout and style The traditional solution is to ensure your email's HTML uses only inline styles that is CSS is used only...

CSS Inlining

Accounts have daily and monthly limit based on their sending plan.

Daily and Monthly Sending Limits

You may see that your daily limit is larger than your monthly limit. In this situation the monthly limit takes precedence and you will be allowed to send to your monthly limit in a single day. 

My daily limit is bigger than my monthly plan limit - which one is correct?

The Starter plans are low-cost plans that make it easy for new or low-volume senders to get started. They include many of SparkPost’s great features, but some features are limited in order to keep costs low. See the chart below for a list of current feature limitations. The Premier plans are robust email packages for high-volume senders that include additional features to facilitate and manage sending large volumes of email.

What is the difference between a “Starter” plan and a “Premier” plan?

Q Why won't my DKIM record verify A While configuring your Sending Domains you need to verify that the DNS entries you have made are available to Spark Post and ES Ps for use The DNS TXT records you create have a TTL Time To Live value associated with them...

My DKIM Won't Verify

List management is pretty important to senders and Spark Post customers are no different Because Spark Post is largely transactional there is no dedupe function when you are sending messages Thus if you have duplicates in a list they will be sent additional emails There are a few reasons why...

Does SparkPost Dedupe?

If you send mail through SMTP rather than REST there are a few errors that are specific to Spark Post The list below covers each of them as well as what to do when you receive them For error messages that are not listed below see one of the popular...

Error messages when using SMTP

Gmail shows mailing list information for messages I sent but I did not use a mailing list Gmail pulls the mailing list information from the list unsubscribe header that we add to all non transactional messages We do this as a means to provide all recipients the option of unsubscribing...

Gmail Shows Mailing List

Both Spark Post and Spark Post Enterprise employ the same settings for message retries including message expiration settings i e the maximum amount of time we will retry a message before we fail it for max attempts and retry intervals which is the time between successive delivery attempts Messages that...

How Are Messages Retried?

“If you never send from your Free account, after 3 months we will close your account, or if you don’t send from your Free SparkPost account for 6 months we will close your account”

“What happens if I don’t use my Free SparkPost account?”

Your plan settings will remain as they are now. If you need a larger daily limit, please upgrade to one of our new plans. Please note that daily limits are always based on your account’s sending performance and history with SparkPost and are reviewed on a case by case basis.

If I stay on my plan, can I increase my daily limits?

Injection Phase For all messages you pass to Spark Post defined as accepted in REST transmissions or 250 Ok for SMTP injections an injection event OR one of three error events is logged An injection event is recorded if Spark Post is able to generate a message and queue it...

How can I account for all messages attempted through SparkPost?

There are a few reasons why you may not be seeing open click data for your transmissions Please review the following list of conditions and configurations to debug your open click data not displaying If you're using a Template in your transmissions does the template have the Open Tracking and...

I'm Missing Click/Open Data

Outlining the changes to the navigation inside the SparkPost app.

Navigation change

In order to explain what Out Of Band bounces or OBB sometimes also called Asynchronous Bounces are we first need to understand how a recipient server accepts email In most cases a recipient server will either accept or reject an email as it comes in In those cases it will...

What are Out of Band Bounces (OBB)?

When you create a new webhook in the Spark Post UI you may see an error similar to the following This error occurs when Spark Post sends a test batch to your webhook endpoint and if an error is detected during that test this error is shown There are a...

Webhook Error: "POST to webhook target URL failed"

Sometimes when we communicate with you as a user, we ask you to identify your account by providing your username, account ID, or account email address. Having this info allows us to help you faster in situations where we don't already have these details about who you are.

Where do I find my username, account ID, or account email address?

Question I received this error 554 5 7 1 recipient address was suppressed due to customer policy What does it mean How can I send to this email address Answer So the error message in the response you received is actually telling you why that particular email address is not...

554 5.7.1 - Recipient address was suppressed due to customer policy

The system policy that this error is referring to is actually our suppression list Spark Post has its own suppression list that encompasses many alias email addresses that are often sent to by spammer and malware senders An example of this would be unsubscribe and in some cases individual email...

554 5.7.1 - Recipient address was suppressed due to system policy

If you are getting a Relaying denied error while trying to connect to smtp sparkpostmail com it is likely because you are not connecting to our SMTP endpoint using SSL STARTTLS and AUTH LOGIN Please check that You are using port 587 or port 2525 when connecting from a Google...

Relaying Denied error

Spark Post provides two options for pulling bounce info from Spark Post a push mechanism and a pull mechanism This article will explain both solutions in detail so that you may choose the one most appropriate to your use case and expertise Push Mechanism Webhooks The push mechanism that Spark...

How Do I Retrieve Bounce Info from SparkPost?

Sender ID is known to fail when using mail-tester to check emails

Sender ID and SPF Failures

If you are having problems connecting to Spark Post over SMTP here's a checklist of things to verify The SMTP server name should be smtp sparkpostmail com or on some systems tls smtp sparkpostmail com The port should be 587 Alternately port 2525 can be used in environments where port...

SMTP Connection Problems

SparkPost EU FAQ

SparkPost doesn't store images for you If you are not using a front end application such as On Gage where you can store your images we recommend the following Upload images to a publicly accessible server or a reputable image hosting service Then link to the image URL in...

Why Can't I Store Images?

User guide for raising a support case with the team

Submitting a support case

To ensure the highest degree of security and stability for our customers, SparkPost will be disabling a number of insecure TLS and stream cipher protocols on October 15. These include TLSv1, ECDHE-RSA-RC4-SHA, RC4-MD5, and RC4-SHA. This change will affect both REST and SMTP injection endpoints

What Secure Ciphers does SparkPost Support?

It can take a minute for suppression events like spam complaints unsubscribe requests and hard bounces permanent failure variety to be collected and processed Once a recipient is added to the suppression list subsequent attempts to deliver to that recipient will result in a Admin Failure code 25 In the...

Suppression timing

The final disposition for all messages sent from Spark Post is either delivered or bounced but messages can be delayed and delivery retried a number of times before the final state is determined Delays aka Temporary Failures or 4 xx Errors When we receive a 4 xx rejection from the...

Message Delivery: Understanding Delays and Bounces

Update on Pricing

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How Do I Test Using the Sink Server on SparkPost?

Q I tried sending after configuring my sending domain but it didn't go through I m getting the error that it's not configured I did not configure DKIM because I was sending via SMTP Why is it necessary A As a leader in the sending industry your sending reputation and...

Why do we need to configure DKIM to send anything?

If your domain’s status is "Blocked", it’s generally because your domain is already in use by another SparkPost account, your domain has been previously blocked for sending abusive traffic through our service or another provider, or because one or more of our requirements are not met

Why is my domain blocked?

Welcome to SparkPost! Get familiar with our product and explore its features.

What are Role Based Domains Role based domains like admin help sales are email addresses that are not associated with a particular person but rather with a company department position or group of recipients Spark Post now provides the capability to verify your sending domains using abuse and postmaster role...

The Benefits of Setting up Role Domains  (postmaster@ and abuse@)

Before you can use the Spark Post REST APIs or SMTP injection you will need to have a valid Spark Post API key Below are the steps you will need to create a Spark Post API key IMPORTANT Make sure to copy and paste the API key when it...

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Create a Template Once you understand how to send an email transmission you'll want to know how to create templates in Spark Post Currently there are two ways you can create templates in Spark Post Create templates in Spark Post using the app Create templates in Spark Post using the...

Creating A Template

This guide outlines some of the different ways you can do engagement tracking with SparkPost

Getting Started with Engagement Tracking

This guide describes the steps you’ll need to follow to start sending mail using SparkPost.

Getting Started with SparkPost

This guide will help you find the best resource for your inquiry and fastest resolution As a general rule first search in the latest API docs and knowledge base articles and then try the following Service Status Find out whether the service is up down sideways on vacation or going...

How to get Help

In the Spark Post UI you can use the Preview mode of the template editor to render your HTML or text templates and send tests of your template There are some limitations on test sends you can only send up to five 5 people at a time DO NOT USE...

Previewing and Sending Test Emails

To protect the sending reputation of all of our customers, SparkPost sending and bounce domains must be officially verified and validated.

Requirements For Sending and Bounce Domains

How to set up domains and verify DNS Records.

Setting up Domains

When signing up for a Spark Post account it’s important to us that you use an email address where we’ll be able to reach you We use your email address to communicate with you about things like Resetting your password in case you lose it Issues related to billing and...

Signing up with a valid email address

What counts towards your daily and monthly usage All targeted injections including messages you send and attempt to send count toward your daily and monthly usage and sending limits These include Messages that are accepted by Spark Post including those sent to a sinkhole address This is the Injected count...

What counts towards your daily and monthly usage?

Getting Started

How to use SparkPost with other 3rd party applications

The following steps will walk you through using Spark Post with Atom Park Software's Atomic Mail Sender Click on Common Settings under the Settings menu and select the SMTP Tab Click on the green sign to set up a new SMTP account and enter the information in as shown Set...

Using SparkPost with Atomic Mail Sender

Background API Keys Spark Post uses API keys as authentication tokens you include an API key in each of your requests to identify yourself with Spark Post and for us serve you appropriately As a result your API keys must be considered secret since they identify you and enable API...

Calling SparkPost From The Browser

The following steps will walk you through using Spark Post with e 3 Software's Direct Mail for Mac First you need to enable SMTP Access check out Direct Mail's article here http directmailmac com support article 232 Set up a new Mail Server profile and configure as below The password...

Using SparkPost with DirectMail

To use Spark Post with Discourse you’ll need to Sign up for a Spark Post account Create and verify a sending domain in Spark Post Create an API key in Spark Post Install Discourse Update the SMTP credentials in your Discourse config Change the default from email Discourse uses to...

Using SparkPost with Discourse

Note this article covers using Spark Post via SMTP with Django We also offer a Python client library that includes a Django email backend The simplest way to use Spark Post in your Django project is to configure its SMTP backend To configure Django’s SMTP backend put the following lines...

Using SparkPost with Django

The following steps will walk you through using Spark Post with Lmh Soft's e Campaign 11 Click on Accounts to go to the Email Account Manager Click on the New button to set up a new SMTP profile and enter your name email address and reply to note that the...

Using SparkPost with eCampaign 11

Using Spark Post with G Lock Software's Easy Mail 7 is easy Just click on Add Outgoing Mail Server Account in the Getting Started window Then set up a new profile for your Spark Post account entering your From Name Email address Reply E mail address and Organization name don't...

Using SparkPost with EasyMail

This article assumes you are familiar with Elixir and the mix and iex CL Is We also assume that you have created an API key with the Send via SMTP permission This article will show you how to use Spark Post via SMTP with Elixir and the Mailman library mix...

Using SparkPost with Elixir

Configuring Exim 4 to use Spark Post as the SMTP relay is very similar to the process described in this Ask Ubuntu com article Instead of your Gmail username use SMTP Injection and for your password use an API key you have generated from your Spark Post account with the...

Using SparkPost with Exim

The following steps will walk you through using Spark Post with Infacta's Group Mail Go to the Accounts dialog and set up a New Account Enter your details on the main account settings page as appropriate IMPORTANT The email address and reply to address MUST be set to an address...

Using SparkPost with Group-Mail

The following steps will walk you through using Spark Post with Infacta's Hoolie NOTE Please make sure you have upgraded your version of Hoolie to the latest version that includes updated SSL and TLS support Version 1 9389 or later When running Hoolie click on Preferences and go to the...

Using SparkPost with Hoolie

Configuring Joomla to use Spark Post is very straightforward since it can be done from its administration panel Add Sending Domain to Spark Post Create an API Key with Send via SMTP permission Login to admin panel as an Administrator of your Joomla installation Open Server tab from System Global...

Using SparkPost with Joomla

The following article will walk you through integrating Mac Mail to use your Spark Post account for outgoing mail and how to configure Mac Mail to use the Spark Post SMTP API to enable open and click tracking To start you will need A Mac with Mac Mail Spark Post...

Using SparkPost with Mac Mail

This article will show how to send email from Magento through Spark Post These instructions assume that you are using the excellent SMTP Pro extension and have a Spark Post account with a verified sending domain Follow these steps to configure Magento and SMTP Pro to send through your Spark...

Using SparkPost with Magento

To use Spark Post with Mail Wizz click on the Servers section of the Mail Wizz interface Then click on Delivery Servers Click on Create new server and select Sparkpost Web Api from the drop down menu and enter the following information Your Name A valid API key you have...

Using SparkPost with MailWizz

Setting up Marketing Rocket to use the Spark Post integration is simple and takes only a couple of minutes To correctly authenticate setup SparkPost to send emails with your domain follow these steps Log Into your SparkPost account Go to Configuration Sending Domains ADD NEW DOMAIN Enter the...

Setting Up Marketing Rocket with SparkPost!

To send email Microsoft Windows PowerShell through SparkPost, there are only a few things you need to do First create a Spark Post account if you don't already have one Next create an API key with the Send via SMTP permission

Sending email from Microsoft Windows PowerShell through SparkPost

To connect your Spark Post account into the Ongage platform log into your Spark Post account and do the following Set up your desired Sending Domain the domain you want to send email from on Ongage such as myawesomedomain com make sure the domain is verified after you've set up...

Using SparkPost with the Ongage Email Marketing Platform

We had several customers using Interspire Email Marketer reporting an issue blocking them from using Spark Post to send email via SMTP This article will address What issue was experienced Test harness Environment Configuration Root cause of the issue What code overcame the issue Applying the patch to your Interspire...

How to patch Interspire Email Marketer to work with SparkPost

PHP List ships with PHP Mailer hence it’s very easy to configure it to send emails through Spark Post SMTP Follow these instructions to configure PHP List Add a Sending Domain to Spark Post Create an API Key with Send via SMTP permission In your PHP List installation open config...

Using SparkPost with PHPList

You can configure PHPBB to use Spark Post either while setting up a fresh new forum or by modifying settings of an existing forum For a new forum we recommend you to configure it after the forum installation is completed as the E mail Configuration step in the installation process...

Using SparkPost with PHPBB

To use Spark Post as an SMTP relay for Postfix create an API key with the Send via SMTP permission enabled then enter the following into your Postfix config file typically main cf smtpsaslauth enable yes smtpsaslpasswordmaps static SMTP Injection your API key relayhost smtp sparkpostmail com 587 smtpsaslsecurity options...

Using SparkPost with Postfix

The Power BI content pack for Spark Post allows you to extract valuable datasets from your Spark Post account all into one insightful dashboard Using the Spark Post content pack you can visualize your overall email statistics including domains campaigns and engagement by ISP Connect to the Spark Post content...

Power BI Content Pack and SparkPost

If you’re interested in relaying mail through Power MTA to Spark Post there are only a few things you need to do First create a Spark Post account if you don't already have one Next create an API key with the Send via SMTP permission Now create and verify the...

Using SparkPost with PowerMTA

To use Spark Post as your SMTP Relay with Send Blaster click Send under the Messages Menu on the left hand navigation to bring up a dialogue box and follow these steps Set up your Sender e mail address to be an address from one of your Spark Post verified...

Using SparkPost with SendBlaster

To connect your Spark Post account with Send With Us Transactional Email Management you will need A valid Spark Post account A verified configured Sending Domain for use with Spark Post Your Spark Post account password A valid Spark Post API Key A valid Send With Us account Once you...

Using SparkPost with the SendWithUs

Signals Integration

The following steps will walk you through using Spark Post with Thunder Mailer Click on Connections and bring up the list of SMTP servers Click on the green symbol to create a new SMTP server profile and enter the information as shown Set the SMTP Mail Server name to smtp...

Using SparkPost with Thunder Mailer

When using stored templates with the Spark Post Word Press plugin we pass through substitution data that you can use as variables in your template to specify some dynamic settings content the main body of the email subject the subject of the email from the email address of the sender...

Dedicated IPs - full-circle reverse DNS and EHLO hostnames on SparkPost

EHLO hostnames in the outbound SMTP conversation#

EHLO hostnames in the outbound SMTP conversation