Reply address masking and From-header

[Sync]

Could someone please point me to where the "Reply address masking" is explained?


And while we're at it (and because I guess it's related): Since yesterday i get mails through spamgourmet with a different From:-line.
e.g. Mails from The.sender.address@domain.tld to my address test1.<my_username>@dfgh.net now show this as From:
The.sender.address@domain.tld [+test1+<my_username>+<some_number>.The.sender.address#domain.tld@spamgourmet.com]

I didn't change any settings so I confess that I'm confused.

[SysKoll]

This happens when you turn on the address masking in the advanced tab. It allows your reply to go back to SG, which then rewrites the email headers to make it look like it came from your SG email address. Read the explanations in the advanced tab.