Troubleshoot IIS SMTP cannot send a letter

iis|smtp| Solution

These days colleagues reflect the online post office can not send a letter, after testing really found that, recall, these days due to the slow speed of the server, suspected of being attacked and set in the IP settings port filtering, only open 25,110,80 and other ports, but also modified the security settings SMTP;

But after careful examination, found that the modified still not, on Google check, see a post, is about the Post Office System and IIS SMTP conflict things just dawned.

Server installed a set of mail system, occupy 25 and 110, after installation I have the port of SMTP to 2525, this time the port filter is not open 2525 ports, so SMTP can not send a letter, it seems that they are really old.

System:

Argo Mail Server
Smtp:25
pop3:110

IIS SMTP
smtp:2525

This allows you to use Outlook to send and receive letters, or you can use CDO letters in ASP.