What Happens When I Delete My Mail
From mail2web.com Wiki
What happens when I delete my mail?
Deleting email messages when using the mail2web.com application will actually delete those selected messages from your mail server. These messages are not retrievable after they have been deleted. Be very careful how you use this option. If you are unsure, wait until you are using your regular email client (which will save local copies of your mail onto your computer) before deleting the message. Messages can be deleted by either selecting them individually (clicking the box next to the message number) and then clicking the "Delete Selected Messages" button, or all messages in your inbox can be deleted by clicking the "Delete All Messages" button.
NOTE: A relatively small number of mail servers are configured to delete email messages after they have been read once, regardless of how the user views their messages. After a user logs into the system to read their messages, the mail server will automatically flag those messages for deletion. It is the responsibility of the user to confirm that their email server does not automatically delete messages after they are read. mail2web.com is not responsible in any way if the user's email server deletes for any reason any of the user's messages.