Hi, using Thunderbird 78.10.0 (64-Bit). Since a couple of days I can only receive mails, but not send mails anymore. When opening a new mail and entering the mail address, the mail address to who I want to send the mail to turns to red. I can also enter subject and enter a message, but when pressing button "Send" then nothing happens. I can also save the mail as a draft, but when opening the mail then again the mail address has disappeared. The whole mail got saved, besides the mail address. As I'm handling several mail accounts via Thunderbird, I made a backup of the settings, then uninstalled Thunderbird, made a restart, installed Thunderbird again and loaded the backup. I've also installed the latest Thunderbird version again over the existing one ... problem still exists. Any idea what the problem could be? Thank you.