rewrite source addresses that send to a distribution list

[msmcknight]

I have an alias (list) set up to relay mails to several people as a group. ie. myfriends@example.com

The problem I am running into is that my SMTP relay provider won't relay emails that come from domains that aren't mine. For example, if friend@gmail.com sends an email to myfriends@example.com, it gets sent to 5-10 people in the myfriends group, but since the source is gmail.com and not example.com, my relay provider is blocking it.

Is there a way to tell zimbra that emails that come from friend@gmail.com should be re-written so they appear to come from friend@example.com before they pass through the MTAs and are delivered to local mailboxes or forwarded outbound again as part of an alias?

[jhurley]

This is a known issue and we are currently working on a solution within Sender Rewrite Scheme (SRS).
The current workaround is to have the message delivered to an account and then use an account filter rule to forward the messages to external users.

[msmcknight]

How do I set it up in practice? So far, every forwarding mechanism fails...

I've set up an account and have tried both:
Prefs -> Mail -> Message Arrival: Forward a copy to:

and
Prefs -> Filters -> Incoming Filters -> (conditions) -> Perform Actions =Redirect to Address

and both of them retain the original senders address in the From header as well as in the original SPF section. As a result, the relay still rejects it.

In both cases, it follows the desired flow and gets forwarded, but the forwarded message still says "From: sender@otherdomain.com"

But -- If I manually forward the message, the "From" field is change to @mydomain.com and the relay accepts it.
It's like the automated forwarding mechanisms aren't actually automating a forward from the account, but rather trying to simply bounce the message unmodified to the forwardee.