How to change from-address when using gmail smtp server

Question

I want to send an email from A to B,with HEADER and CONTENT through gmail.

How to do that by PHP?<

Answer 1

If the reason you want to use gmail is because you don't want to set up an MTA (the reason you stated in a comment to this answer), you have 2 options:

1. If the web server is at your home/work place; use your ISP's smtp-server
2. If the web server is at a dedicated hosting center, ask them what smtp-server to use.