iMac 24" M4, MacOS 15.5, Mail v.16.0 (3826.600.51.1.1)
Apple Mail’s Trash mailbox, under Settings/Mailbox Behaviors, is set to “Erase deleted messages: Never.” However, it definitely does delete trashed mail after 30 days. It did not delete trashed mail when I ran it occasionally several years ago (nor did Thunderbird). Is this a bug, or have I missed some setting?
Check with any server-side settings.
Assuming you are using IMAP to access your mail, that Trash folder is a server-side folder. The server may have retention policies that are deleting messages independently of Apple’s Mail app. Log on to your mail provider’s web interface and review your settings to see if there is something you can change.
If, however, your Trash folder is a local folder on your Mac and not an IMAP folder, then it may well be a bug in the Mail app.
That having been said, if you want to retain old messages, why are you putting them in the Trash folder? Its intent is (and always has been) a place to temporarily hold deleted messages in case you later change you mind. If you want an archive of old messages, you should create a special folder for that purpose instead.
Thanks for the quick reply! The IMAP account is my own domain which is handled by Apple. I trash messages quickly, but selectively empty the trash when the matters are completed. This used to work fine when I normally used Thunderbird, but occasionally used Mail; then, Mail never lost anything.
I forgot to mention that my iPhone is also set to “Deleted Messages/Remove/Never” (no iPad), as is iCloud.
Bottom line: “Never” should mean “never”! That shouldn’t be an option if the server prohibits it, so I gather that it’s a bug in Mail for either the iPhone, iCloud, or the Mac.
Client-side behavior and server-side behavior are independent of each other, even if both sides are maintained by Apple. Email clients don’t have the ability to prevent the server from deleting things, and I’m not aware of any protocol to communicate such settings between server and client. It’s not a bug in your client if the server is deleting the messages; it’s simply something the client can’t do anything about.
Always remember: in technology, nothing works the way you think it should. Things work the way the people who made them think they should, and then only when they make them correctly. (Government seems to operate on a similar principle.) Expected or designed behavior is not a bug, no matter how nonsensical it may appear to a user.
Before my father passed a few years ago, I was constantly butting heads during “Tech Support for Dad” because he couldn’t accept that he couldn’t just demand the machine to do things the way he thought it should. He’s the only person I’ve ever seen be unable to understand the basics of the original TiVo interface.
All that said, I’m not saying you’re not experiencing a bug. But the fact that the client doesn’t know the server’s retention policy is not a bug, no matter how stupid it may be.
Granted. But the server did not delete trashed mail before. And it’s not documented. And data loss is a thing—a big no-no!
But my question is, do I have something screwed up that I haven’t thought of yet?
I suspect the deletion is done via a server-side policy when your email is hosted by Apple. See Delete email in Mail on iCloud.com:
There is something you can do about it: move your trash off the server.
Settings > Accounts > [your account] > Mailbox Behaviors;
Set Trash Mailbox to On My Mac
Are you looking at the iPhone settings for MESSAGES or for EMAIL? On my I phone it looks like those are separate settings.
That is confusing! Mailbox behaviors actually says “move discarded messages into Deleted Mailbox.” Definitely email, though.
The only fly in that ointment is that no other computer/device can access it. Sort of like going back to POP. I might try a new folder, maybe labeled “Sort Through.”
I noticed that the documentation for Mail’s configuration includes this:
One option/workaround is to not store your deleted messages in the server’s trash folder. Instead, create a folder (“PermaTrash”, perhaps?). Then configure Mail to move messages there when you delete them. The server will see this as an ordinary folder and shouldn’t auto-delete them.
Or you can stop deleting messages when you want them out of your inbox and instead archive them, which should move them to an “archive” folder (which you can configure).
See also:
Excellent idea, and thanks for a great name!
Oddly, even though I created a mailbox named “PermaTrash” and quit/relaunched Mail, there’s no folder named “PermaTrash”; instead, it seems to have changed its name to just “Trash,” with a trash icon!
But it works fine so far (we’ll see in a month…), though it still says “PermaTrash” under Settings/Mailbox Behaviors. Anyway, thanks again!
Check on the server (e.g. via its web interface). Maybe the Mail app always presents your configured trash folder the same way, regardless of its actual name.
How can I tell? It’s still named Trash, and it has a trash-can icon. 
I tested this with both a Fastmail account and iCloud account, and Mail does appear to present the chosen folder as Trash despite the actual folder name. With an iCloud account, the list of folders in Mail should display the folder Permatrash as Trash and the server-side trash folder as Deleted Messages.
Grrr 
…no way to know whether this solves the >30-day problem until next month!
Don’t look from within the Mail app. Instead, log on to the server’s web interface and look at the folders you see there.
Interesting! It’s named PermaTrash on iCloud, and it has the stuff in it going back to 1 July, so maybe it will last more than 30 days. I suspect that you can mark this problem “resolved.” Thank you yet again!
In my experience with the mail apps on MacOS and mobile OSes with custom junk/spam folders, whatever you designate as a junk folder gets treated as a junk folder, and setting like delete anything older than 30 days (a setting I prefer and always use) is respected for that folder. I suspect the same is true for a trash folder.
So perhaps moving messages that you don’t really want trashed to a custom folder, or using the archive folder for messages you do not want deleted after 30 days, is a better move than trying to create a custom trash folder.
But I guess, as you say, you will know for sure in a few days, when things that are now at close to the 30 days deleted stage reach 30 days.