How to set up a custom Return-Path in Postmark

If you use Postmark to send emails you might receive a deliverability recommendation saying "Set up a custom Return-Path" for your domain. This is an important step to take in order to ensure DMARC compliance, and here's how to do it.

Find your custom return-path

Log into your Postmark account and then select "Sender Signatures" in the top menu bar. In the list of your domains you should be able to see one of them highlighted with "Return-Path Not Verified" in red text. Click the DNS Settinngs link next to that.

On the DNS Settings page you should see a row with "Return-Path" and "Inactive". This is what we need to verify. By default, Postmark suggests you use pm-bounces as the return path. Unless you have special requirements, just use the default.

Next to it is the CNAME value you need to add to your DNS records: pm.mtasv.net.

Update your DNS records

How you actually add that value depends on your DNS provider, ie the service that hosts your domain name. Since most providers have their own ways of doing things, the following steps are somewhat vague. In general the process is:

Log into your DNS provider and find the domain in question.
Somewhere under the domain settings, you should find a place where you can add a CNAME record. If you're lucky the button is named exactly that, or if you're a bit more unluck, you might be looking for "Edit zone" or something to that effect.
Create the CNAME record.

Example using Gandi.net

For this example, I am using gandi.net to give you a sense of the process.

After logging in, I find the domain I need to modify. Under "DNS Records" I click the "Add" button. I then choose "CNAME" as the type of record I want to add.

In the fields that appear I enter the following:

TTL/Unit: Leave them at the defaults
Name: This needs to be the name of the return-path you want to use. We've opted for the default, so I enter pm-bounces. If you've changed it to something else in Postmark, you'd need to enter something else here.
Hostname: This is where we enter the value from Postmark: pm.mtasv.net. Note that in some DNS systems (like Gandi.net), we need to add a dot at the end of hostname values so the full value becomes pm.mtasv.net..
Click Create

Voila, your DNS record has been created.

Verify the changes in Postmark

Head back to Postmarks DNS Settings interface where you found the original values. It is now time to click that "Verify" button to the right of your "Return-Path". If everything is correct, you should see a green checkmark and a "Verified" message!

Custom Return-Path verified on Postmark

In some cases, you might need to wait a bit before your DNS record changes take hold. If that's the case, you won't get the verified message, but don't worry; just come back a little later and try again.