A while back, I posted an inquiry about sending mail that disappears or is
routed to bulk/spam folders. I never got a reply to it. I also saw quite a
few posts about issues with Exchange plopping messages in the turf folder or
killing them off entirely. I did a little experimenting and came up with
this very simple solution:
When using CDO, you *must* provide valid values for both the .Sender and
..From fields in the mail object.
All of the documentation I came across only shows using one or the other,
but not both. It appears that the various antispam strategies look at one
or the other (or both). If the one (or both) that a particular server looks
at is missing or invalid, assumes the message is bogus and it discards it
(AOL, Earthlink), or (in the case of Hotmail and Yahoo), routes the message
to the bulk mail folder instead of the inbox. (It's interesting to note
that when I was testing, sending messages from Outlook to domains that were
chucking messages coming from a mailer script worked fine. From looking at
the headers of the received messages, Outlook is filling in both fields for
you behind the scenes.)
It is also extremely important that you provide valid return addressing.
Many strategies use address verification to determine if the sender at least
exists, so if you put in an address that your domain won't resolve for a
RCPT (i.e., dont.reply@mydomain.com), the message most likely won't be
delivered.
And, for those who can't understand why they get sessions that abort with
"550" errors, it's most likely due to the IP address of the machine
initiating the session being in a block designated as dialup/portable
addresses (the case with most residential DSL and cable ISPs) and/or it does
not have an MX record designating it as a mail server in DNS. If you get
these errors, you will need to take it up with your connectivity provider to
get a static IP or get your existing static IP designated as non-portable,
and an MX record. You could also try making nice with the admin of the
server you're trying to reach to get them to whitelist you or give you
credentials for SMTP AUTH with them.
Thanks to the low-life spammers for making things such a pain.
