Error while moving message to mailbox ‘(null)’
It all began a week ago when I updated to El Capitan. Shiny new interface with some great new Mac Mail features to look forward to. Marvellous.
But that’s when the trouble started.
After a couple of days, one of my 11 IMAP mailboxes decided that when I deleted an email it would give me an error: “An error occurred while moving messages to mailbox ‘(null)’”
Helpful? Not.
Some of the time the message would delete. Other times it would not.
I deleted the email account, added it again. Rebuilt the mailbox. Deleted the envelope files. Removed the cached saved states. Everything. And no, it did not go away.
A day or so later, another mailbox started to do the same. Followed by a 1 hour support call to Apple which did nothing to alleviate the problem.
Then came the OS X 10.11.1 update which included “important updates to Mac Mail.” Great, I hoped they had fixed this bug as it was costing me much time.
But, no. It only got worse.
Another mailbox started to complain about the same thing AND it wouldn’t let me copy emails between IMAP mailboxes as I used to. Since this is the easy way for me to share emails with other parties (e.g. moving invoices from my personal mailbox to the accounts mailbox ready for the accountant without needing to actually forward it) and critical to my daily workflow I got back on to tech support.
The Fix
It turned out to be something remarkably simple and not a bug per se. Although in my first experience with the error (OS X 10.11) I had not changed anything, when I upgraded to 10.11.1 I had switched off the automatic download of attachments on all mailboxes.
It turns out that with IMAP in Mac Mail under El Capitan, you MUST tick the box and download attachments by default (so much for saving space) otherwise when you try to delete or move an email some weird stuff happens between your Mac and the mail server and errors appear (my guess is that the local message is compared to the server message and, since they do not match as the attachment is not downloaded, the server sends a warning/error). Once the tick was in place on all accounts, all the errors went away. (Note that the IMAP path prefix and port are specific to your email server and may vary.)
When you upgrade to El Capitan, I suggest you go through each IMAP email account you have and do the following. On my machine the OS update did not migrate the setting properly, so a manual reset may save you the troubles I had.
- Untick the download attachments option
- Save the account update (e.g. by clicking on another mail account)
- Repeat for all mail accounts
- Quit mail
- Open mail
- Tick the download attachments option
- Save the account update (e.g. by clicking on another mail account)
- Repeat for all mail accounts
- Quit mail
- You should be good to go!
Remember to recommend the article if you are experiencing the same issue. Thanks for reading.
