Mail authentication error?

[Paul Howarth]

Gordon Messmer wrote:
> Hongwei Li wrote:
>>
>> Recently, users say that they cannot use Outlook to send emails out if 
>> they
>> set SSL connection with port 587 for outgoing server and 993 for incoming
>> server.
> 
> Port 587 isn't an "SSL" port.  It's the MSA port, and probably supports 
> TLS.  If Outlook is configured to do SSL rather than TLS, it's not going 
> to work.
> 
> Port 465 is the SMTP "SSL" port.

In my experience Outlook is much happier doing submission using port 465 
rather than 587.

I turn on port 465 as follows in sendmail.mc:

DAEMON_OPTIONS(`Port=smtps, Name=TLSMTA, M=s')dnl

Then configure the Outlook clients to use port 465 instead of 587.

Paul.