I have an email account on my domain, e.g [email protected]
And on my dedicated server mysite.com I redirect messages from [email protected] to [email protected]
Now, if an external user like [email protected] sends me an email to [email protected], it properly lands in Gmail but in spam and Gmail headers says that SPF failed, because example.com doesn't designate mysite.com as a permitted sender.
Is there something I can do about this? It doesn't sound right, mysite.com should not claim that is sending email for [email protected], it should just be labeled somehow as a redirect (from [email protected] to [email protected]).
The behaviour you describe (passing envelope sender through unchanged) is traditionally how mail forwarding has behaved. After all if there's a problem with delivery that's where errors need to go.
To avoid SPF issues forwarding services can use SRS1 to construct a new (local) envelope sender address which routes to the original.