09-07-2014 04:55 PM
TO: Admin of SMTP.VERIZON.NET
Please remove CRAM-MD5 as a supported authentication type for SMTP.VERIZON.NET. The server does not actually support this auth type, and some clients fail authentication when they mistakenly try to authenticate with this method. While many email clients can fail, fallback to other methods listed, and succeed, some clients (such as printers with scan to email functions) are not able to fallback quickly enough.
If your server doesn't support the AUTH method, it shouldn't be advertised. The troubleshooting proving this error has been posted on several forums since the change a couple months ago. Banning CRAM-MD5 seems to work well where the client allows that practice, but again, some clients don't let you choose that specifically.
PLEASE, PLEASE, PLEASE, fix it or remove it.
250-AUTH DIGEST-MD5 PLAIN LOGIN CRAM-MD5