IP Warming 101 Basics: Shared or Dedicated IPs

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In this article we'll look at: 

  • Mail Transfer Agents (MTAs) 
  • IP Warming: Shared vs. Dedicated IP Addresses
  • 3 Tips to build your sender reputation correctly

Many factors must be taken into account when it comes to IP Warming. Proper IP warming reduces deliverability issues.  Your sender reputation will thank you later for all the hard work put into it.  

To achieve maximum deliverability, avoid the spam folder, and maintain a healthy sender reputation, there are many factors that must be thought out and implemented correctly before sending your first email campaign.

 

Mail Transfer Agents (MTAs)

When it comes to IP warming, it is vital first to understand how message transfer agents (MTAs) work.  

Sending MTAs are responsible for relaying emails from the sender to the right recipient, just like a mailman. 

Receiving MTAs decide what happens to the emails it receives. MTAs keep track of each and every activity by analyzing and storing the recipient list in order to also perform future routing functions. 

MTAs are also crucial because they send the auto-responses when an email is not delivered to its intended destination. Email bounces are also essential as they contain important information that can help you work on any challenges your email campaign encounters. Here are some examples of what MTAs might send back to you:

 

Hotmail:
‘’’5.7.1 Unfortunately, messages from [123.321.231.31] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [VI1EUR04FT027.eop-eur04.prod.protection.outlook.com]’’’

With the above error, you have probably overwhelmed the recipient server side and you need to pause and review your list. Once the sending list has been reviewed, you should start sending again but at a slower pace to Hotmail in order to monitor the reaction. We would also suggest getting in touch with Microsoft in order to ask them to unblock.



Yahoo:

‘’’4.7.0 [TSS04] Messages from 321.123.123.1 temporarily deferred due to unexpected volume or user complaints - 4.16.55.1; see https://postmaster.verizonmedia.com/error-codes‘’’

This particular message means that you have been sending too fast and/or your emails were considered as spam. I suggest to stop sending to Yahoo for an hour (make a pause), review the list and start sending again with less aggressive settings, like max 400 emails per hour + limiting your outbound connections to 5 and 5 emails send per connection.




The receiving MTAs are configured with limits on incoming mail, (e.g. to decrease the amount of spam received), and if those limits are exceeded, the sending mail server may be identified as untrustworthy and will affect the delivery of those emails. Some receiving MTAs also care about authentication, while others have very strong spam control (filters?). These are just a few of the reasons why IP warming is necessary as it allows you to build a relationship with your recipient’s infrastructure.

 

IP Warming: Shared vs. Dedicated IP Address

When it comes to IP warming, many things need to be taken into consideration. Are you controlling the process from A to Z, or are some factors being decided by different parties?

 

Shared IPs

A shared IP environment is a group of IP addresses used by a company such as Cakemail or Netcore. Multiple senders are sharing the space and the reputation, to a degree. The advantage of a shared IP pool are that a shared IP address is much cheaper than a dedicated IP address. It also helps you develop an IP reputation even if your sending volume is low.

The disadvantage is that using shared IPs makes you dependent on other senders following best practices. Their bad behavior will impact your deliverability, and this is completely out of your control. 

Keep in mind an email marketing service provider is responsible for identifying and blocking abusive senders, keeping them from impacting your reputation. Many mechanisms are put into place to ensure that the abusive behavior is either detected immediately or before it even happens.

 

Dedicated IPs

Contrary to shared IPs, dedicated ones are unique to the sender. They aren’t shared with other companies or senders which means you control their reputation with all and any actions or decisions you make when sending.

When it comes to dedicated IP addresses, especially new ones, they always appear suspicious to ISPs as they have little to no sender reputation. To ensure you build your sender reputation correctly, you need to keep in mind the following:

 

Good email engagement

A good sender reputation is based on a mix of positive responses from your engaged users or subscribers and the ISP's history of you.


When sending an email to a subscriber, the factors determining whether or not you make it to the inbox are your sender domain reputation, your sending volume, the quality of your email list, and how engaged your subscribers are with your content.

If you send an email and a majority of your subscribers don’t open or interact with it, the ISPs might take it as a sign that your email isn’t exactly solicited. This can also happen with human or bot openers and clickers.  User engagement will be high, however, when you transition over to your real list, the engagement will differ greatly.  All the time and effort you put into warming up your IPs and your sender reputation goes down the drain. 

Good engagement and email metrics also includes keeping spam complaints and bounces at bay. The first time you start sending emails with new IPs is not the moment to show with certainty that your emails are not wanted.

During an IP warm-up your brand, domain, and sending reputation are always constantly being looked at and recalculated. 

 

Sender Reputation

Sender reputation is critical,  especially if you have a negative sending history. If you have issues elsewhere, those issues will transfer over to your brand new IPs. Your sender reputation follows you everywhere you go. You must fix the root cause before starting to warm up your IPs.

If you have a sender history but haven't monitored your reputation, an email audit might help you see any pain points you can fix before migrating toward a dedicated IP. You wouldn’t want all of your hard work to be wasted because of an issue you weren’t aware of that was easy to fix.

 

Clean Lists - Good Quality Lists

When starting to warm up IPs, create a warm-up schedule.  You must start sending first to your most reliable subscribers who engage with your business and you frequently. This can be done by looking at past campaigns or on reliable data you have accumulated on your subscribers.

Another easy way to ensure you have the best possible data would be to send to subscribers who have opted-in. If you haven’t cleaned your lists in a while, segmentation based on engagement with a list hygiene check will ensure you start your dedicated IP warm-up journey correctly.

If you have a list of subscribers with the trifecta (high engagement, opt-in list only, and a list hygiene check), you will kickstart your IP warm-up correctly.

 

Conclusion

 In an email, everything is based on the relationships you create, whether they be with ISPs or subscribers.  You want to ensure that you remain consistent in all aspects of your email infrastructure and strategy.

Remember that IP warmup is not needed only when you are migrating towards new IPs or when sending from a new sender domain. Warmups are necessary when you stop being consistent. If you send emails and then stop for a month, you will have to restart sending slowly to rebuild the relationship and reputation with your subscriber’s inboxes.



Day

traffic per IP

# of MTA connections

#emails per connection

1

500

1

1

2

750

1

1

3

1200

2

2

4

1500

2

2

5

3000

3

3

6

5000

3

3

7

10000

4

4

8

20000

4

4

9

40000

6

6

10

80000

6

6

11

130000

8

8

12

180000

8

8

13

250000

12

12

14

350000

14

14

15

400000

16

16

16

550000

16

16

17

700000

20

20

18

850000

20

20

19

1000000

25

25

20

1000000

25

25

* Target 1 million
 

About the Authors:

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Yanna-Torry Aspraki, Business Development & Deliverability, EmailConsul

Sitting on the executive team at the intersection of Sales, Product, Marketing, and Growth, YT helps drive the company forward in a market in desperate need of accessible and reliable deliverability tools, while representing EmailConsul in places email & deliverability have never been before.

 

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Sergey Syerkin, Founder, EmailConsul

Sergey has exceptional knowledge when it comes to email and deliverability on compliance and operational perspective. With over 13 years of experience, he is now working on expanding his own monitoring product, EmailConsul, in order to ensure all senders have the data they need to make the right decisions.

 

EmailConsul

Accessible email analytics and deliverability platform focused on giving all necessary data and power into the hands of the sender.

 

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