Make sure open relay is not enabled on your Exchange server, and that you
have a DNS PTR record to match your public IP A and MX records. You can
check to see if you're being blacklisted by going to www.dnsstuff.com and
doing a Spam Database Lookup using your Exchange server's public IP address.
You can apply to be removed from most real-time blacklists (RBLs) as long as
you have your DNS correctly set up and are very sure that you are not
sending spam from your domain.
To find out if a specific ISP or domain is blocking you, open a telnet
session to their mail server on port 25 (you can get the MX record IP for
any domain from DNSStuff). If you are being blocked you will likely see a
message stating that your IP address is being blocked with a contact number
or URL where you can apply for removal. I've just gone through the lengthy
and frustrating process of removing our new office IP address from a number
of RBLs and ISP blacklists. It turned out that our ISP has assigned us an IP
block that had previously been blacklisted for open relay, so even if your
Exchange server is secure and DNS is correct this is no guarantee that
you're not being blocked.
Keith W
Post by p***@bigpond.net.auAm having a problem with an MS Exchange server that I set up last
month. Some domains - including hotmail - will not accept email from
this exchange server. Cause will either be "Delivery delayed" or
"SMTP relay denied. "
Could anyone please assist - it's driving me nuts
Thank you