I have PostFix installed and working to send/receive email.
However, my requirement is for this MTA to only receive inbound email from gmail.
The background is that this server runs a product support system and only accepts email sent to email@example.com where myhost.com email is hosted by gmail.
So firstname.lastname@example.org is configured to forward to the local PostFix MTA that converts the emails into tickets in the product support system.
The PostFix MTA must completely refuse any email from any other IP addresses than gmail MTA servers. And, additionally, if possible, it must only accept incoming email from email@example.com
The product support server sits behind a linksys router. So port forwarding on port 25 in the router sends email to the local machine.
Is there a way to reject any communications except from gmail ip addresses?
Or, failing that, can PostFix be configured to only accept connections from gmail ip addresses?
Or, failing that, can PostFix be configured to reject email from any other ip addresses even if it does initially accept the connection?
Essentially we want outsource dealing with spam to gmail. Plus it's simpler to configure and monitor email received to firstname.lastname@example.org via the gmail website.