As a precautionary measure to stop spam, many ISPs are no longer allowing outbound traffic on port 25. As a result, your ISP may have blocked port 25 on your account. Port 25 is the standard TCP port used to send e-mail via the SMTP protocol. Hopefully AuthSMTP servers also offer their services through port 2525. So, if MaxBulk Mailer can't connect to your server through default port 25 simply use 2525 as shown on this page. If the 'MD5 Challenge-Response' authentication scheme gives problems try 'LOGIN' or 'PLAIN' from the second pull-down menu next to 'Authentication'.
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