Talking deliverability with your next Email Service Provider

When trying to find the right email marketing software, we often look at a platform’s feature set, but we should also pay particular attention to a vendor’s level of expertise. This is where a vendor can prove their weight in gold.

Deliverability is one of those areas that is critical, but often overlooked or misunderstood.

Common Deliverability questions for an ESP

The questions marketers ask about deliverability often relate to their specific line of business; e-commerce retailers are going to have different priorities than affiliate marketers. Having said that, one of the most frequently asked questions relates to inbox placement and how to increase deliverability rates with specific ISPs (Internet Service Providers).

Yahoo and Gmail are often the ISPs of greatest concern. Both of these ISPs pay significant attention to user feedback from recipients. Users move messages between the inbox and junk folders and report email as spam which significantly affects the reputation of a sender.

report spam

Better not have them report spam! Other user feedback is also used as a filter.

So deliverability also has a non-technical side – ensure that your emails are relevant and of value. The right message delivered to the right person at the right time is an email that a subscriber wants in their inbox.

Deliverability questions you should ask an ESP before signing up

It’s quite easy to find advanced email marketing technology these days, but it’s not as easy to find the same level of support. A customer’s deliverability success begins with personal and proactive support from their ESP and that’s the foundation for a long term relationship.

Deliverability support
Most of the official support can be found in your Service Level Agreement, but a lot of it will also be based on your own intuition and the discussions you had with your prospective email marketing company.

You shouldn’t hold back with your deliverability questions, for instance, ask them:

  • How will you respond in the case of a black listing?
  • What should I do when a specific ISP is blocking my emails?
  • How many 1000’s of emails can I send to this ISP per hour?

No matter if you have a self-service or full-service ESP, Email marketing software support is an important consideration to take into account when it comes to potential deliverability problems.

Deliverability reporting capabilities

Once you’re sure that you’ll have the appropriate level of support; Then it is wise to look into the deliverability reporting capabilities of the ESP, and not just at the bounce and open ratios.

Some ESPs can group domain families and break down the deliverability performance per specific IP addresses. For example, see the Outlook domains below. Or Yahoo, which owns,,


Grouping these domains allows you to see how a specific IP address performs with each ISP. It also allows the ESP to do something called IP-routing if you are using a shared IP pool, or using multiple IPs.

The ESP can route traffic share to an ISP across the best-performing IP addresses.

Domain family deliverability report
A domain family deliverability report view in ExpertSender

Aggregation of domains into a domain family can give a more holistic view without going into the details of each domain separately and this helps with segmentation and analysing deliverability performance.

In the image above you can find an example of a domain family deliverability report. (click for full-size)

A proactive approach to avoiding deliverability problems

Avoiding email deliverability problems is always a better strategy than trying to fix them later. You want to proactively mitigate them before they occur. An email marketer can expect an ESP to ask them important vetting questions and interview them to find out exactly how long their subscribers have been on their lists, how they were collected and how frequently they had been receiving communications.

In addition to this, it’s also very important to ensure that any email address that generated hard bounces or had complaints submitted had been removed prior to sending.


Deliverability and your first campaign

You need to ensure that you have a sound subscription process on the customer’s website. Furthermore, it should be very clear what type of content a subscriber might expect once they’ve signed up. Ideally, you should give the subscriber choices as to what type of content they’d like to receive.

Is re-permission needed?

If you haven’t been sending to your list for a long time or obtained it through 3rd parties, then this could have a significant impact on your IP reputation. In such cases, it would be wise to consider running a re-permission campaign that will verify which email addresses are in fact valid and active.

Email marketing is a long-term proposition, you might lose some subscribers with a re-permission campaign, but avoiding deliverability problems in the long term will make this more than worthwhile.

Be patient and you’ll be rewarded in the future

Customers are often anxious to send emails to their entire list immediately when they sign up, but it’s wiser to send to a more engaged audience first as every dedicated IP space requires an IP warm up phase to build a solid reputation with different ISPs.

Building your volume gradually across a few weeks will allow you to send larger volumes in the future, so it’s worthwhile being patient as you’ll be rewarded in the future.

About Krzysztof Jarecki

Krzysztof has been professionally involved in the email marketing industry since 2003. Initially, on the programming front, then later, focusing on email deliverability and online marketing best practices. Today, as the CEO of ExpertSender he leads the company into the multichannel marketing platform market.
He is an active participant in key international email industry organizations, including, MAAWG, ESPC, EEC, Signal Spam and the Internet Society of China. Krzysztof is a contributing writer for several online email marketing publications.
Strategically, he is engaged in product research and development, while overseeing the relationships with ISPs and the biggest customers in the USA, Europe, Russia and Asia.

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