Hi I'm using mint 18.3 and recently I've lost the use of my send/reply email thunderbird, recive is OK this appears when I attempt to send or reply - An error occurred while sending mail: The mail server sent an incorrect greeting: icp-osb-irony-out2.ii
Apologies for the email problem. If you have not already tried resetting your email client settings, then please try that first. There was a fairly recent certificate update that may have affected the way your email client is responding to the server. You can update the email settings by temporarily setting them to a default setting or using a different email setting than the one you're currently using. After you save your changed settings, you can then return them to their original settings. Check to see if your Thunderbird email client is correctly working after that.
If the problem persists after resetting your email client, then we recommend that you contact our live technical support team.
If you have any further questions or comments, please let us know.