E-mail account-properties-stationery-signature-select signature, and you can do it.

The second problem is that some mailboxes have this function (for example, 163). What if they don't?

Step 1: email account-properties-send email-default bcc, tick and write down your email address (version 6.5 provides this function, please upgrade if your Foxmail is below 6.5).

Step 2: Set up the mail server. Most of them have the function of automatic mail filtering, and a filtering rule is added to it, that is, when the sender of the received mail is himself, just save the mail to the "Sent" folder.

I hope I can help you!