about half a year ago we started having problems with forwarding emails to some servers including Gmail etc. It seems that Google and others have started to enforce a strict SPF policy and forwarded emails from domains with strict SPF settings are no longer accepted.
A solution to this problem seems to be the so-called SRS or Sender Rewriting Scheme, which rewrites the sender’s address. The procedure and patch for qmail is available here. However it seems it is not included in qmail distributed with Interworx.
It is very surprising that no one has asked about this problem here on the forum yet. Are we the only ones who have encountered it? Does Interworx include some other solution for it?
I can honestly say this has never come up, before. Can you provide more information as to google blocking forwarded messages? No one has ever reported that as an issue, though it is well known that Google expects domains to have SPF, DKIM, and PTR records. It would be odd for google to block messages from domains that have SPF records.
Thanks,
-Jenna
Friendly Neighborhood InterWorx Support Manager
SRS allows a mail server to rewrite the From address to allow the middleman mail server to forward on a received email without triggering SPF restrictions from the forwarded recipient mail server.
This solves the problem that mail forwarding (alias) accounts have. For example, mail sent by Google to somealiasaddress@interworxhosteddomain.bfr which is a mail forwarder that then relays the mail to the final destination address finaluser865432@outlook.-com. Outlook.-com would look at the header and refuse the mail because the “interworxhosteddomain.bfr” mail server is not allowed to send mail for google. SRS adjusts the header so that outlook.-com won’t refuse it because the header makes it clear the message is being forwarded from “Interworxhosteddomain.bfr”.
A lot of mail servers have adopted this because otherwise forwarding received mail won’t work for mail servers that check SPF on receipt. It’s been a thing, for example, on Plesk (Linux) and cPanel servers for a long time.
It would be very useful to have the option to enable this.
I talked to the dev team and submitted a feature request, though I do not have an ETA at this time.
Note–both cPanel and Plesk use Exim for their mail service, not qmail, so there is a bit of a difference as to how something like this would be handled, just in general.
I know the stacks are different, but Muad already linked to the qmail patch and, like it or not, cPanel and Plesk are exactly the products Interworx gets compared to. Most end users don’t care about the stack (the how), only the feature set (the what). It may not be fair, but such is the world.
Anyway, thanks for considering the feature. Getting forwarding working again would be useful.