I tried the fix and no luck. Actually, if I open the attachment immediately, it is there but after 2 minutes not good any more! Very frustrating. I may have to ditch Thunderbird and just work with Outlook.
I have the same problem. And it is only with my email. The jpg and pdf attached files I receive are corrupted. My husband is on the same Thunderbird email and his attachments all open correctly. Mine open OK in Outlook but not in Thunderbird. Su...