MailChimp Email Addresses Look Weird in Outlook? Here’s How to Fix It.

Originially published on Medium on September 22, 2016.

The Problem #

I get emails from lots of organizations that use MailChimp. How can I tell that they use MailChimp? Because their emails always start like this:

Sender <person=example.com@mail215.atl61.mcsv.net> on behalf of Sender <person@example.com>

I use Office 365 at work and usually browse email in Outlook. And every single MailChimp email I receive that way has a garbled From address just like above.

Because the email is sent by MailChimp’s servers, the From address usually includes the domain of that MailChimp server. This causes three problems:

  1. It’s ugly.
  2. I might think it’s spam.
  3. I can never whitelist emails from your domain because it’s never your domain — it’s always a different MailChimp server!

This is fairly easy to fix. All you need to do are make a few DNS tweaks to your domain and your emails will no longer show this garbled mess in the From field in Outlook.

##The Fix

All you need to do are add two DNS records.

Type:  CNAME
Host:  k1._domainkey.example.com
Value: dkim.mcsv.net

Type:  TXT
Host:  example.com
Value: v=spf1 include:servers.mcsv.net ?all

That’s it! Once you’ve added/modified these DNS records, your email addresses sent from MailChimp to Outlook clients will look just fine!

You may already have a TXT record that begins v=spf1, in which case you just need to add include:servers.mcsv.net to the list of domains already in that record.

##The Explanation

When Outlook shows the garbled From address in the first place, it’s because it doesn’t know if it should trust the MailChimp server as a legitimate sender for your domain. DKIM and SPF records are designed to help email servers know who can or cannot legitimately send mail on behalf of a domain. With these records in place, emails will correctly display as Sender <person@example.com> because Outlook has a way to verify that MailChimp is authorized to send mail for the example.com domain.