Does Gmail support return receipt of an email ?
This is not available using the usual web interface.
If you want read receipts you will have to activate POP3 access on your Gmail account and configure an email client that supports reciepts - such as MS Outlook, Outlook Express or Thunderbird.
If you want to stick with using the web interface you can sign up for ReadNotify this is a paid subscription service where by any email you send, you send it through their servers and they provide read receipts. They also provide other information and notifications.
Spypig is free web service to do this but not always reliable.
Since support of read receipt highly depends on the receiving server/client. If the receiving server clients are not able to support it, then sender may never get a receipt. And we can not know before hand that the receiving server client will support this or not. This kind of feature is actually mostly used for the environment where receiving side is using the same server e.g. Microsoft Exchange Server.