What you have posted there looks like a text representation of the start of a PDF file.

SO just perhaps your anti virus is corrupting the attached PDF files.

Thanks for the response Matt, but it can't be a anti-virus program because it happens on multiple window based computers with various users in our office using Thunderbird, some of the computers use different virus programs. However, when we access with another mail program like Outlook or Apple mail on a Mac, the email is fine and easy to read. One other note, if we open the email on our Iphone THEN forward it to ourselves, then access the email in Thunderbird, it opens fine. This only started happening within the last week. We have been getting emails from this customer for over a year in the same PDF format without a problem.

Please can we keep it in the public forum.

Without message source it is hard to say what is different. But it looks to me like the messages are being corrupted somehow. If not by anti virus, have you got a new router or internet modem? Or one of those ever popular spam devices or an off site spam filter.

The customer is using a program called appfolio.com to create the email, but I don't think that helps you.

The modem and router haven't been changed in years. I guess it will remain a mystery.

JerryMannix said

The customer is using a program called appfolio.com to create the email, but I don't think that helps you. The modem and router haven't been changed in years. I guess it will remain a mystery.

Do you have anything you can send me to look at, to see what the cause is? Or try to!

I assume not all the mails are critically confidential.