Encryption in Mozilla Mail
N.B.: These instructions apply to both Mozilla Mail and Thunderbird mail and to the Macintosh versions of these programs.
Open Mozilla.
Go to Window > Mail and Newsgroups.Go to Edit > Mail and Newsgroups Account Settings.
On the sidebar, click Server Settings.
Check the box Use Secure Connection (SSL).On the sidebar, click Outgoing Server (SMTP).
Check the box TLS, if available.
Click OK and the window will close.