My RR mail stopped sending after several weeks working perfect with the 587 fix. I had been warned by a RR CSR that this might happen. I'm not sure why or if it was something else that went wrong but i tried everything I knew to get it going again, re entering everything, trying the 465 number, trying the cwmx.com alone etc etc. Finally after rereading much info on this thread and the various links I got it working again today.
What finally worked for me was entering cwmx.com:25 in the smtp box with no username and password and setting the SSL to off. Bingo I could send mail again and all mail stored in out box went on through. I do not know if the :25 is the vital part of it or not and don't want to risk testing to see if it works without it -- am leaving well enough alone for now!
I got there for rereading this entire thread.
On the phone again with RR this morning, they said again that it is a security/spam reason for not allowing it (send mail from non RR site). They did offer one solution which is to acquire a businesss email address but with one of these you are apparently limited to that one address and would of course require changing all your email accounts or starting over from scratch -- not good alternatives. but they did say with that kind of account you could send email from any remote location WiFi or smartphone.
Re Invincibles post #58 with the info from the Apple Knowledge base. In it there is a link to the following ATT info on the problemo
*AT&T outgoing e-mail (SMTP) server policy
AT&T outgoing e-mail (SMTP) server policy
What are the AT&T outgoing e-mail (SMTP) server names?
ISP E-mail servers
AT&T will provide support for sending E-mail using AT&T owned and operated outgoing server addresses:
• Former AT&T Wireless customers use "smtp.mymmode.com" (Standard POP/IMAP compatible via port 25 with*no SSL.)
• AT&T*customers use "cwmx.com" (Standard POP/IMAP compatible via port 25 with*no SSL.)
The configuration and use of any other outgoing server address will not be supported due to several factors including, but not limited to, the inability for the outgoing server to authenticate users (whether by IP or username/password) that are not directly connected to that Internet Service Providers network. This is mainly done to prevent unsolicited users from sending SPAM via the ISPs servers.