When setting up a Sending Domain for your invitations/triggers etc. you are likely to want to use a domain that closely matches your normal web domains e.g. firstname.lastname@example.org and not simply the email address linked to the account which might be email@example.com.
However, once you have set up the verified domain and are able to use it from the SmartSurvey App, when used for survey invitations, the Return-Path (the email address that errors are sent to) must point to the SmartSurvey mail servers, usually at smartsurveyuser.com. This is to allow us to track the emails sent out.
Using a Return-Path that doesn't match your sending domain, which is what happens by default, causes "alignment" to be broken and although it is a common scenario for third-party email tools, in the most strict cases, it might cause the email to be scored badly for SPAM. At the very least, it would prevent you from using DMARC to try and apply stricter rules to emails from your domains.
SmartSurvey now allows you to setup a bounce domain that needs to match the domain or a sub-domain of your sending domain and which will need to CNAME back to smartsurvey. You might choose:
Bounce domain/Return-Path: bounce.example.com
If you set this up, when SmartSurvey sends out emails on your behalf, we will append a random identifier to the bounce domain and use that as the Return-Path. This will cause alignment between your "from" address and Return-Path, allowing you to use DMARC and also reducing the chances of mail going to SPAM.
Note that DMARC alignment must be set to "relaxed" (the default) in order to permit alignment between the organisational domain (example.com above) and the sub-domain (bounce.example.com above). If your alignment is strict, the policy will fail and the action you specify will be carried out.
It is not mandatory but if possible is recommended to be used.
Setting it up is as simple as creating the CNAME displayed in the sending domain page and then pressing verify. If there is a value in the bounce domain box and it does not verify, the domain will not verify. If the box is blank, verification will be skipped and survey invitations will use a SmartSurvey domain for the Return-Path.