What Does International Email Deliverability Look Like?

What Does International Email Deliverability Look Like?

It’s not a mystery that today’s US market is largely dominated by a limited number of mailbox providers such as Google, Microsoft and Verizon Media (Yahoo, AOL and Verizon). And this is not necessarily a bad thing. Users benefit from these free, fast, and reliable mailboxes with their advanced anti-spam filters.

From a deliverability perspective, it’s not hard to see the advantage as well.

While these email providers differ from each other, they’re also consistent in their own way; if you “follow the rules” (ie. ActiveCampaign’s deliverability guide to Gmail) you shouldn’t encounter deliverability surprises because a good amount of contacts use these mailboxes.

In other words, if you “do your homework” with these 3 mailbox providers you cover approximately 80-90% of your contact list.

However, this is not always the case when reviewing the international market. In some European countries, global providers (Google, Microsoft, and Verizon Media) mailboxes are way less predominant and local providers are truly the masters.

In Poland, for example, over 70% of the active mailboxes are from Polish providers. In other countries like Germany, France, or Italy, the global providers have almost the same share as local providers. This is also true if you look at countries like:

  • Czech Republic
  • Ukraine
  • Russia
  • China
  • South Korea
  • Japan

Each of these countries has its own local providers with their own peculiar “rules”.

As you can imagine, this introduces more complexity if you want to improve your deliverability globally. Despite all the differences among them, they all have something in common you should be aware of in order to improve your deliverability.

Be respectful of their limited amount of resources

First off, let me address the ugly truth: international local providers don’t have the same resources as Google, Microsoft, or Verizon Media.

This means that local providers can be more susceptible to outages, especially during peak hours. It’s a good idea to take this into consideration while scheduling your campaigns. Also, avoid sending emails at the hour on the hour. Many senders schedule campaigns for the top of the hour, which floods the provider with emails – which can lead to difficulties in processing.

For the same reason, it’s more important than ever to segment your list and be more mindful about your email cadence.

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Content Optimization is more relevant than you think

It’s not unusual for a local mailbox provider in Europe to be protected by renowned third-party spam filters such as Proofpoint (Cloudmark), SpamAssassin, and VadeSecure. Apart from that, they tend to rely on “more traditional” in-house solutions that account for things like domain authentication and message content.

The good news is that those are factors you can easily control and improve. Content best practices for deliverability are often underestimated but they can truly make the difference, especially with these providers.

Here are some best practices you should consider when optimizing your content:

  • Optimize your images: Keep them light in weight! Every single image should be smaller than 50kb (ideally <20kb). Feel free to slice bigger images in smaller parts to meet this suggested value on each of them.
  • Avoid URL shorteners: While convenient, this method is often blocklisted on the provider side to avoid potential abuse.
  • Avoid spammy content: What year is it? Well, on some providers spammy words are still a thing!

Email Authentication: don’t forget SPF

Authentication is not something to overlook. DKIM (Domain Keys Identified Mail) and DMARC (Domain-based Message Authentication, Reporting, and Conformance) tend to have a big impact.

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Also with regards to authentication, local providers could attach more weight to overlooked aspects. Be sure to have a valid SPF (Sender Policy Framework), complete with all the IPs you use, on your sending domain. ActiveCampaign does this for you, but here’s how to add an SPF record if you want added coverage.

Sender’s Certifications in Europe

You may be familiar with Validity’s (Return Path) Certification program, a safelist that provides benefits at global mailbox providers.

However, other certifications exist.

CSA Certification

Certified Senders Alliance (CSA) is a German-based certification with more than 1,000 members across Europe. The main goal of CSA is to increase the quality of commercial emails: in exchange for a number of benefits (mostly related to german providers), members have to meet high legal and technical standards required for the membership itself.

While their benefits could be more relevant for Germany, using their admission requirements as a checklist is an excellent way to comply with up-to-date standards in the industry and, ultimately, improve your deliverability.


Poland, being one of the most peculiar markets, has its own IP certification called TrustedSender. Members will be whitelisted on Onet, WP, o2, Interia (no transfer limits, no spam filtering) and have access to reputation data. Members will also be marked as “TrustedSender” on contact mailboxes.

Getting in touch with international providers

If your legitimate emails are being filtered by a specific mailbox provider despite all your efforts, you might need to get in touch with the provider itself. Remember, you should contact them as a last resort.

If you want to increase the chances of receiving a reply follow these suggestions:

  • Be sure that you are doing everything “right”
  • Do your research
  • Run some tests
  • Be polite and respectful
  • Provide as much information as possible (to help them help you)
  • Use the recipient’s language (Use Google Translate if you must!)

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