Send the email to google workspace relay if the recipient does not exist locally

[jrd082210]

Hi,

Is it possible to configure the DMS to forward the email to google workspace relay if the user does not exist locally?
for example test1@domain.com, test2@domain.com, and test3@domain.com is available on DMS then test4@domain.com is on google workspace.

DMS was already configured and can send and receive emails locally and externally.

test1@domain.com can send an email to test2@domain.com and test3@domain.com but cannot send to test4@domain.com which is hosted in google workspace.

Its just that when sending to test4@domain.com email will bounce automatically.
Also, DMS was already configured in google workspace route. So we don't have an issue on receiving email from google workspace with same domain.

Hope someone can help us.

Thank you!

[polarathene]

DMS will assume it is managing the mail domain if you have it configured to receive mail for it to a mailbox or alias address.

You can use an alias to forward to an external address like @gmail.com but from what you're saying the other mail server is also configured to use the same mail domain? (presumably without any MX record pointing to it, only to DMS?).

Forwarding mail is easier when you have specific addresses or no overlapping mail domain. Postfix does support changing the transport for delivery with transport maps config but to accept the traffic for addresses that aren't known, you'd likely need to go with something like relay_domains (no official DMS support), and potentially using the local mailbox addresses that DMS does know as a way to determine "send mail for these accounts to Dovecot, and for all other recipients forward to this server".

It should be possible to work something like that out, but there is no official support for such with DMS, nor do I have the time to figure that out on your behalf. If you browse the Postfix docs for main.cf + master.cf config, it should be doable.

You can likely setup to instances of DMS to reproduce that setup you have and experiment locally until you get the config figured for production usage. Our repo has a demo directory with a couple examples, one of those is 3 instances of DMS setup for a sender, relay and receiver.