John D. Hardin wrote:
Is there a non-abusive way to automatically verify an email address is
valid? Verification does not need to occur in real-time; large delay
is acceptable. It is not intended as any sort of attack/abuse/spam
prevention or mitigation strategy. A given address will not be checked
more than once. There may not be any email message headers associated
with the address.
If this is drifting off topic, let's kill it and I'll find someplace
more appropriate.
Yes - there is. I'm using Exim and if you aren't using Exim you might
not be able to do the things I can do. It's SAV done right.
Exim provides caching so it minimizes real callouts. Youalso have to do
things in the right order. You do the greylisting/blacklisting first.
You then exclude all the spammer only tricks like impersonating your
domain(s) and other stuff that only spammers do. You then verify the
recipient exists first. After doing all this the sender verification
traffic is minimal.
Now if someone wants to invent a better way that would be great. I'd
like to see some sort of DNS based way to do this but until there's
something better SAV is it.