This section is on the OutMail Settings page, in the SMTP Relay Settings section.
The Return Address is the address that bounce messages will be sent to. Usually it is not used for other purposes such as sending normal reply messages to. Some ISPs use the Return Address as a means of verifying that a user is allowed to send mail through their servers, so if it is set incorrectly, they may reject your mail. The return address is not normally visible in message headers, and it is NOT necessarily the same as the From: address or Reply-To: address in the message headers.
By default VPOP3 uses the return address specified in the original message, but in some cases this will not work, so VPOP3 will let you change it to something else. There are three possible options
Use Default - This tells VPOP3 to use the return address specified in the original message
Always set to the address - This tells VPOP3 to always set the return address to the address specified.
Set non-local return addresses to - This tells VPOP3 to check the return address specified in the original message and see if it matches the Local Domains specified on the Local Mail tab. If it does, then it leaves the address as it is, if the address isn't a local one, then it will change it to the address specified.
