Disable a Users ablity to change the "from" field?

[Himanshu]

What about users who use an IMAP client such as Thunderbird?

1. You can Put SMTP Restrictions to allow mail sending only from Specific Mail IDS
2. You can Force Auth , when Sending mails . So when User Sends mail he/she has to Authenticate . In this case
whenever s mail is sent an AUth ID would be Logged and would be visible in Headers. So one can know who sent
an email , if this was not a Mail From ID that was supposed to be sent from.