Maintaining the Return-path

This feature should only be used in rare situations, when a recipient domain is incapable of processing emails sent to it that use VERP.

In rare situations, a recipient mail server may look at the Return-path email address (otherwise known as the 'envelope sender') of an email, and be unable to properly process the email if the Return-path email address has been adjusted to use VERP (which is standard practice for all email service providers).

This inability to handle any VERP email address is typically only found in older systems such as email-to-fax services, email-to-SMS services (a side note: instead of using email-to-SMS services, we strongly advise using SMS Messaging), and messageboard systems. 

This feature is available at 'Settings > Sending Options > Advanced > Maintain Return-Path'.

It is important to note the following about this feature:

• Only certain recipient domains are allowed to be added - these are domains that we have previously determined to not properly accept emails using VERP. Contact our support team if you are sure you need to add a domain that is not allowed.
• Emails you send to recipient domains using this feature won't use VERP (and will just use your original sender email address), so you'll need to add include:spf.smtp2go.com to the SPF record of your sender domain name.
• Any bounces that happen after the 'SMTP transaction' has completed will not show up in our App, as we have no way of receiving them.