These days, colleagues reflected that the online post office can't send a letter. After testing, I really found it. Recall it. For a few days, because the server is slow, it is suspected to be attacked and port filtering in IP settings, only open 25,110, 80 and other ports have also modified SMTP security settings;
But after a careful examination, I still can't find the revision, go to Google to check, see a post, is a matter of changing the post office system and IIS SMTP conflict.
The server has installed a set of mail systems, which takes up 25 and 110. After installation, I once changed the SMTP port to 2525. This port filtering did not open 2525 ports, so SMTP could not send it, it seems that he is really Big.
system:
Argo Mail Server SMTP: 25POP3: 110
IIS SMTPSMTP: 2525
This allows you to use Outlook to send a letter or you can use CDO in ASP.
