Hi there, I was using Thunderbird 32 bit version 78.12.0. So I always receive emails from one department, then I must attach the PDF file from that email to another email for our clients. Normally I must save the attachment to my computer first, then on the email to my client I attach the file from my computer. BUT, being lazy as I am... I decide not to save the file to my computer, but instead I drag and drop the file from received email... to the new email window which I already prepared for my client. To my suprise, between the last 3 months (and I do this daily for about 5 to 10 emails), I received total 6 respond from my various clients that I wrongfully attach the file. When I check the send folder, I found my email was attached with the correct file name. But when I open the PDF file, it contain the different file (the PDF which used to be send to another client). I checked my inbox, and found that I received the email with correct PDF name and also correct content. 6 cases from about 750 emails sound like a minority report, but this is wrong and dangerously for my business. Therefore I tried to re-produce the error, and here is my finding so far: - If those wrong email I do the drag and drop once more... the sent email will keep mistakenly attach the same file (correct name, but consistently using the wrong content). - If I create new mail, to the same destination address, with the different subject, then I do drag and drop once more, the attachment is correct. - The incorrect content were randomly picked by the Thunderbird (?), sometimes it's from the nearest attachment in the same date, or a day before... but sometime from 5 months ago. - I've not use any add on at all (never install any add-on, and I've checked the add on window is empty). Please kindly help me about this? Thank you Stan