The settings here control the name(s) and email address(es) stated as sender when you send out email messages. Depending on the server configuration, you can define multiple sender identities or only adjust the name and other control fields.
This first block contains general properties of the selected sender identity:
Note
The Email field might not be visible or editable. This is no malfunction but a restriction set by the server administrator to prevent users from sending email with faked sender addresses.
Every sender identity can have its own signature text which will be apened to the message text when you start writing a new email message. Visit Settings > Preferences > Composing Messages to configure when and how signatures are inserted.
Unless restricted by the server administrator, the identities list has control buttons for adding and deleting sender identities. If present, click the + icon in the identities list footer to create a new identity. Fill out the form and click Save to create it. The new identity is now added to the list and can be edited or deleted from there.
The Delete button also located in the identities list footer will delete the currently selected identity after displaying a confirmation dialog.