About the port number of the server that sent the message

Today, a small email message, all the parameters are set, the server is not responding.

At first the suspicion was that the mail server was not set up, and the mail server and Outlook were found to be consistent.

Suspect port number 25 is incorrect. Most of the information is said to be 25.

。。。

Later found this page, said

Usually an outgoing server employs port 25:it ' s the default SMTP port. However, some IPs deny its use because of the massive spam and malware traffic by which is affected. This issue was raised in particular when you need to switch to another isp–for instance, when you ' re travelling and Conne Cting to a new provider. In this case you can try to use port 587 or port 465 to avoid the block.

More in Detail:port 587 are supported by almost every outgoing SMTP server and it's useful for unencrypted or TLS connecti Ons While Port 465 are the right choice if your need to connect via SSL.

Excerpt from: HTTP://WWW.SERVERSMTP.COM/EN/PORT-FOR-SMTP

That is: 25 is the default port, may be because of spam and other reasons can not be used, then consider 587. Generally for non-encrypted request 587 can be used.

After modifying the port number to 587, it is OK.

Report:

C # Development mail client uses SmtpClient.

Use principle: Need to set the mail server address, and port number.

About the port number of the server that sent the message