re: Any suggestions for a better email client? This is a Thunderbird forum used by Thunderbird users and help is freely offered by volunteers who - yes you guessed it - they are Thunderbird users as well. You will probably find that all email clients will have issues with something at some point. I prefer Thunderbird because it has less issues than others. You can personalise and self-fix a load of stuff that you might not be able to do in others. At the end of the day, it is your choice.

re :I don’t understand how Mozilla cannot fix a problem that has been occurring for years to almost everyone! How do you know what the thousands of Thunderbird users experience? Personally, I've never had this particular issue, well not in Thunderbird. But I'm sure some have experienced the same or similar as you.

re :It clearly has to do with Thunderbird trying to attach the vcard image of another sender’s prior email I am trying to respond to.

Confirm - this does not occur when you want to send a new Write message; it only occurs when using a 'Reply' to a received email which always has a vcard.

re: trying to attach the vcard image of another sender’s prior email I am trying to respond to In the original email you are trying to 'Reply' to. Is there a signature delimiter - looks like a dash dash -- above the vcard?

Confirm - you do not add your own vcard as your signature.

If you are not adding your own vcard as signature then the 'googled' copy pasted information might not describe your issue. They used a work a round to not save the draft and it resolved it for them. Even if not perfect solution. So I presume you probably tried that and it did not work for you.

Confirm that you switched off auto saving of Drafts as a test before clicking on 'Reply' and it had no effect.

I have an idea which I need some info.

Can you tell me if the mail account is an IMAP mail account ? If yes, You subscribe to see folders. Q: Do you synchronise those subscribed folders so that a copy of the folder is stored in Thunderbird?