We are experiencing problems with your SMTP Client being blocked by mail filters. Before we switched to ASPOSE we used another tool and it worked properly. Now we think we identified the problem as being in the RECEIVED FROM part of the message header:
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Received: from webserver.domain.com ([10.10.1.91]) by EXCHANGE.domain.com with Microsoft SMTPSVC(6.0.3790.1830);
Received: from exchange.domain.com ([10.10.1.91]) by EXCHANGE.domain.com with Microsoft SMTPSVC(6.0.3790.1830);
It appears that when the ASPOSE Send method is run, it connects to the mail server and identifies itself incorrectly by using the host name of the mail server. If the client and mail server are the same server this problem would not be seen, nor would it matter until SPAM filters got involved, but it is causing many problems with our products. The SMTP Client needs to correctly identify itself to the mail server when communicating.
The Code is something like this:
Dim oMailMan As SMTPClient = New Mail.SMTPClient(“exchange.domain.com”)
‘Create Mail Message
The “host” parameter appears to be used as the identifier of the client machine sending the message. This will cause a problem with mail filters when a SMTP client incorrectly identifies itself as the actual mail server instead of its qualified domain name. I would suggest using a reverse DNS lookup or something on the server to identify itself and NOT the host parameter.