To send a digitally signed and encrypted e-mail, just select the Digital Signature and Encryption menu item in the Tools menu or the Signature and Encryption button in the toolbar when writing an e-mail. You can digitally sign and encrypt e-mail messages at the same time, or just digitally sign or encrypt them. To send a digitally signed and encrypted e-mail, you only need to select the Digital Signature and Encryption menu item in the Tools menu or the Signature and Encryption button in the toolbar when writing an e-mail. Mail can be digitally signed and encrypted at the same time, or only digitally signed or encrypted. To send e-mail with digital signature, you need to apply for and install a digital certificate in the system; To send an encrypted message, you must obtain the public key of the recipient's digital certificate.