Every so often, and email will come to me, usually from a client, which has attachments. Most of the time, these attachments are decoded by Mail and I can get to them. However, every now and then, Mail decides not to decode them. The resulting mess of an email is a mix of HTML and Base64 encoded files. Being images, some of these emails can be massive. I’ve been manually copy/pasting the attachments into text files and manually decoding them using the terminal to extract the files.

What I want to do is to either have Mail reprocess them so that they are represented properly (message + saveable attachments), or somehow save the whole message and extract what I need from that. The former is more preferential to the latter as it helps keep things in order.

Also - any ideas as to why this happens? I’ve not been able to track down a solution, but I Google informs me that it’s not a problem I am alone with.

I have the same problem. I've been going to the GMail webmail and downloading the attachments there. It's a right PITA.

I managed to fix it...I had to rebuild the mailbox... ( Mailbox > Rebuild)

It took a while, but it did the job...

Thank you! It seems to have helped here too. I must remember that for the future.