In the pop-up interface, select the email account to which you want to add the signature file on the left, and click Signature Management to start setting.

In the signature management interface, click New directly, and then a small box pops up, which can name the signature file for future management.

In the New Signature box, enter your own signature. In the following options, you can also determine which email address the entered signature is used for, and you can also insert a picture into the signature.

After setting the signature, click Write E-mail. After writing the text, click Insert-Signature and select the signature you just set to insert.