Custom Envelope Sender

Custom Envelope Sender Video Overview

By default, when sending an email to a target, the message will be sent from the supporter’s email address.

This can be problematic for email deliverability, especially with the advance of DMARC, since certain providers restrict delivery using this method. To improve delivery, you can enable a custom envelope which will modify the sender’s email address with a new domain that is authenticated.

The “Reply to” email address is still the supporter’s own, so any targets replying would still be replying to the supporter and not the modified address.

This feature provides a way around the need to ‘spoof’ a supporter’s email address when sending from our servers, and is the recommended option to ensure optimal deliverability.

What will it look like?

The target will receive the email from the supporter, using their first and last names as their display name, and using their names along with the envelope domain for the From email address.

For example, say supporter Elvis Presley ( used the campaign to email a custom target, with an envelope of The target would receive the email from, but if they replied it would go to 

If the First and Last Name fields are not completed, then the target will receive an email from 


  • You need to have a domain ready that will be used to construct the supporter’s sending email address. This can be a subdomain of your own site, or a brand new domain, but shouldn’t be something you are using already. You will need to set this up yourselves. Subdomains can usually be added as part of your domain package. Talk to your IT team if you need help.
  • You need to have SPF, DKIM and Return Path on this domain set up and working. Instructions and verification of this will be shown when adding the envelope domain to your campaign
  • It is recommend to have First and Last Name fields as mandatory on your page since these are used in the construction of the “To” email address

Enabling a Custom Envelope Sender in a campaign

Once you have completed the prerequisites, the ‘Custom Envelope Sender’ settings can be accessed under ‘Sender Settings’ within the ‘Admin’ section of your page.

If you have not used this feature before, there won’t be any custom envelope senders in your account yet. Click on the ‘Manage Senders’ button to add new sender envelopes to your account:

A new sender is added by clicking New Domain:

It is recommended that you do not use a domain that is used in general email broadcasts. For example, if the primary domain for email is, using will help protect email delivery on

In order to make sure that the domain is set up correctly for email deliverability, we perform a series of steps to validate that the domain is suitable for use as a custom envelope sender domain (see here for more regarding your domain authentication). If all the validation steps are successful, you will be able ‘Complete’ the setup. The custom envelope sender is now ready to be selected.

In this example, we’re using the domain ‘’ as the custom sender domain (please do not use this yourselves!).

This means that to recipients, any emails sent to a target contact will appear to come from a ‘’. If the target wishes to reply via email, and simply hits ‘Reply’ in their email client, the Reply-To address will use the actual supporter’s email address and the recipient will still be able to respond directly to the supporter.

Your supporters will not need to do anything differently and won’t even notice that this has been enabled. Responses via email will still be sent to their regular email address, but they may have a lot better chance of getting through to the intended target with their message.



Updated on December 22, 2020

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