AUTH is used to specify SMTP authentication. As of edit 116, EMAILX supports two authentication methods: AUTH=PLAIN and AUTH=LOGIN. You may also specify AUTH=* (or AUTH=AUTO) to have EMAILX query the SMTP server to see which methods it supports, and to then use AUTH=LOGIN or AUTH=PLAIN according to which is supported. If both are supported, it uses AUTH=LOGIN. You can omit AUTH entirely if your SMTP server does not require authentication. (Many SMTP servers distinguish authorized clients by their IP address and thus don't require authentication via username and password.) If you specify AUTH, then you must specify USERNAME and PASSWORD either in the configuration file or in the parameter calling list.
Note that SMTP servers will normally list their supported AUTH options in response to the EHLO message, e.g.
> EHLO microsabio.com
< 250-smtp.abc.xyz.com Hello
250-PIPELINING
250-ENHANCEDSTATUSCODES
250-AUTH LOGIN
etc.
You can see this in the Log file for Loglvl 4 or higher.
In the above case, the server is announcing that it supports just the AUTH LOGIN variation. Some servers, however, will not indicate which AUTH methods it supports until after a secure channel is negotiated, followed by a re-sending of the EHLO command. So the first list might omit the AUTH line, or show it with no options. Then, after the second EHLO, it will report another another list of supported options, similar to the above, but perhaps with variations or additions, corresponding to secure mode.
See Also