running under php-cgi (FastCGI) sending mail from local server (same as website) on A CentOS 5 Dual Core AMD with 4 Gb of ram (oh yeah... and Plesk 9.3)... additionally, I have been able to send other types of mail from D7 but it is refusing to place any emails into the queue. "0 email was added to queue" (sic)
Just a side note.... I have always had problems with the mail functions of Dolphin since 6.1.4 Usually with a bab MIME type error resulting in no "From" field. Simply had to remove all the \r's from their mail construction code... same problem here in D7...just cant find the place in the code where the actual email header is constructed.
I don't think it is related though... this is simply not putting any email into the queue.