Starting on December 19th we’re no longer going to accept mail submitted to our SMTP AUTH system with a URI classified as black, grey, red, or gold on URIBL. These categories contain domains that are either actively used by spammers or found in unsolicited bulk mail. This is currently being treated as a trial change.
The “grey” category is a special case. It contains domains that are used by bulk or commercial mail, which may not be spammers in the strict sense, but are nevertheless against our policy for SMTP AUTH submissions (no bulk or marketing mail).
Our goal is quality of mail through our submission system in order to maintain a high reputation for our customers that depend on us for routine communication. Because we are not a “bulk mail” outfit we are unfortunately unable to accommodate bulk mail use cases, and it would be more appropriate to use the mailer’s service to send bulk mail instead of ours.
If you find you’re having trouble submitting messages after this change, contact support so we can investigate. Marketing-type mail should be sent directly to the intended recipient and not rely on forwarding or resending.