I fought this stupid thing for a good few days with no luck (and loss of sleep, etc.) and I finally found the solution.

I’m using Google’s Apps For Your Domains as the e-mail server for my domain. First, there’s the 2 gigs of storage per user. Also, it’s a nice solution for long-term backup and storage. And I’m most interested in using GMail’s spam filters and spam training, since that’s one thing that is VERY non-simple (non-possible, honestly) with every web hosting solution I’ve seen yet.

Unfortunately, GMail doesn’t allow an IMAP interface (yet, hopefully??  come ON gmail guys!!!). I check my e-mail from multiple machines and POP3 is very unsuited for this purpose (even with the recent:username@ hack which is admittedly interesting). And I just cannot bring myself to using only GMail’s web interface. Call me old-fashioned or whatever, but I just can’t do it. I like being able to use KDE’s excellent PIM applications to manage my mail, contacts, and calendars–and most importantly, sync it all up with my PDA with kpilot. So what I wanted to do was bring the e-mail that I have coming into my GAFYD GMail account into my web host’s IMAP server. Such a simple thing to do, I thought.

I was horribly wrong.

I’ve tried a couple of routes to do this. My first thought was that I could use GMail’s auto-forwarding to push incoming e-mail onto the IMAP server. So I set up a sub-domain that I’d ask my web host to handle mail for and forward all e-mail from GMail to it. The problem was that for some reason I was getting errors like this:

This is an automatically generated Delivery Status Notification

Delivery to the following recipient failed permanently:

[email address]

Technical details of permanent failure:
PERM_FAILURE: SMTP Error (state 9): 550-Verification failed for < [email address]>
550-No Such User Here
550 Sender verify failed

But I couldn’t tell where things were failing. So I started looking at other options.

I tried running fetchmail on my web host and popping mail from gmail into my IMAP server. But unfortunately, my web host doesn’t allow outbound POP+SSL, so that doesn’t work. It also rules out things like using Horde+IMP to fetch mail too. I then tried running fetchmail on my home machine, popping mail from GMail and then forwarding e-mail to my web host’s IMAP server, but my web host doesn’t allow forwarding from my IP address (it knows it’s from a home cable provider). So I went back to looking at the subdomain forwarding problems.

Turns out (thankfully I found this post from a guy with the exact same problem) that the problem was that my web host was trying to verify the username that was being forwarded. Now, the funny thing is that GMail doesn’t just forward for user@domain. I tacks gunk on in the middle, so that what it turns out to be is user+caf_user=subdomain@domain. So my web host tries to verify that e-mail address, which obviously doesn’t exist in the user accounts that it knows about. The problem was that my web host used to be handling my e-mail for my domain, so it was looking internally to verify that e-mail address. The solution, as noted in that post, was to tell my web host that it was not handling e-mail for my domain by changing its MX records to GMail’s MX handlers.

Simple enough solution.  And things seem to be working swimmingly since I fixed that.  HTH somebody else out there.  =:)