What happens when the protected address is down?

General discussion re sg.

What happens when the protected address is down?

Postby lwc » Mon Jul 20, 2009 2:41 pm

Do I lose messages that were sent while my protected address was down? Or do you try sending them again hoping it was fixed by then?
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Postby josh » Tue Jul 21, 2009 5:55 pm

Standard SMTP rules apply. That is, if your server gives a permanent failure code, then you don't get the mail. If it gives a temporary failure code, or can't be reached (except for DNS failure, I think), our server keeps trying for a while. We currently have a fairly standard set of timeouts for this.

We may have to clamp down on this as time goes on - delivery queue buildups have caused big performance problems for us in the past, as our server labored to deliver messages and had less resources available to do what it was supposed to be doing.

Currently, this is actually a big issue as well, since we've moved servers and a number of providers have decided to blacklist our new IP address (which was not originally on any black lists, by the way) and we have to go through the vagaries of convincing them that we're not spammers (and note that we never to manage to convince some providers, who don't seem to want to spend the 5 seconds it would take to look at our web page, but these folks are usually very small and the affected user(s) just have to use another service for their forwarding addresses).

Anyway - long answer I know, but there it is.
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Postby lwc » Wed Jul 22, 2009 1:04 am

But what happens if I discover my protected address is down and change it?

Will your second and forth attempt reach the new protected address (assuming the old had a temporary failure code, or couldn't be reached)?
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Postby josh » Thu Jul 23, 2009 2:22 pm

No - it'll keep trying on the old address.
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Postby DrkShadow » Sat Oct 23, 2010 3:06 pm

Just a thought, it would likely be less overhead and no storage if you build an SMTP proxy. Listen for the RCPT TO line, filter it according to the database, and maybe the first few lines after DATA for bcc, cc, to: headers. Filters in real time, forwards the rest, stores nothing. If the destination server is down, the sender doesn't get to send the message; if it's not, it goes straight through; if it's rejected, the sender SMTP server gets that rejection message back and has to retry later itself, etc.

Seems like a good thing all around. Wouldn't necessarily require more work on the behalf of alternative domains (inboxfree.org), as if they use spamgourmet for the sender or use their own sendmail server, the behavior is approximately the same (difference _possibly_ being they wouldn't forward, and queue, every message through spamgourmet's SMTP server first)
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