Gmail does not list sent items if mail sent from custom smtp server

We have our own company's smtp server. When we send mails using开发者_如何转开发 the above smtp server, the mails do not list in the gmail's sent items. The mail is sent using asp.net What can be done?

Instead of using your own SMTP server, use the SMTP server from GMail. How else can Gmail know that you have send an email.

You have to supply credentials to use Google's SMTP server, so you must store the user's username and password (from Gmail).