I installed Snow Leopard yesterday. When I came down this morning I discovered that all of my rogers.com email boxes had 4 copies of each email in each in box. The me.com mailbox did not have this issue. I put them all off-line when it appeared that copy number 5 was starting to download. The box to delete files on the server had ben reinstated for one of the rogers accounts, which had not been set in Leopard. I have used this computer since late May using Leopard without this problem. Any suggestions? I haven't yet called Apple or Rogers.
I am experiencing a similar issue. Two copies of each message addressed to my company Exchange account. After I open and read one copy, the extra one disappears when I attempt to open it. I have not yet found a work around. I am reluctant to trash my mail prefs file because that action requires that I reenter all my account information for six accounts. Deleting the mail caches and rebuilding them did not remedy the problem.
My experience could be exactly what you mention. I have more than one client checking mail on the POP account that the dupes are coming from. I have not tried your test, but it makes sense and would explain the intervals for when the duplicate trigger occurs. I would assume then that as a reproducible bug, it can be fixed. I had the same setup on Leopard (multiple clients checking the account, multiple machines in fact, including iPhone and iTouch, etc) and never experienced the dupes.
Sorry, I got a telephone call, and resulted in a double post.
It sounds like I could try to test this, then, but noting that all servers will not be equal in this issue. Have you opened Activity monitor on each client, and watched during overlaps in time?
I just got back and, so far, the recreation of MessageUidsAlreadyDownloaded3 after deletion appears to have worked. Interestingly, in the first go round, something did go wrong. I deleted the file after closing Mail then reopened. The messages were downloaded as I expected. However, when I closed Mail after that process completed and then opened it again, the mass download happened immediately again. When I went to check the MessageUidsAlreadyDownloaded3 file, I noticed another filed called MessageUidsAlreadyDownloaded3.corrupt with a modified date stamp indicating that it had been the one Mail created the first time after I deleted it. So, something went wrong in the recreation to force MessageUidsAlreadyDownloaded3 to have to be created yet again. I did not notice this .corrupt file in the directory before, so I believe this was the first time (creation time stamp on the .corrupt file was from the time when the first download started, seemingly reinforcing this).
I have opened my other Mail client to let it check for mail on the POP account and did a manual sync on my iPhone. So far, OS X Mail has not re-downloaded. I did delete the dupes but have not emptied the trash in an attempt to minimize variables in case the dupes download again.
For reference, the POP account is a Yahoo! one and the other desktop client is Zimbra. I'd prefer to use Mail only, but Yahoo! will only offer IMAP functionality through Zimbra on the desktop (on the iPhone Yahoo! Mail will do both IMAP with Push). If Zimbra was better, I might use it for all my accounts for the sake of simplicity, but I personally don't like it.
OK so I followed Ernie's suggestion and it worked for about 30 minutes.... then it went back again, to downloading thousands of duplicates on every check for mail.
I just got back from three days away. My POP accounts are being accessed from a blackberry, iPod Touch and webmail. Only the Snow Leopard mail seems to have this problem with duplicates, and this situation has run without a problem under Leopard since May 2009.
I deleted the MessageUidsAlreadyDownloaded3 file and this appears to have halted the duplication. The only annoying thin is that one of my Rogers accounts had all of the files on the server deleted - even through this had not been set on the last version of Leopard. Fortunately, I have a backup on Time Capsule...
So far so good for me. I deleted the dupes from yesterday, have opened and closed Mail several times, have checked the POP account from the other client and my iPhone. The dupes have not been re-downloaded. Thanks for the tip Ernie.
Ok, that's bizarre. I sat down at my comp just now after being away for a couple of hours. What do I see? The mass download happening again. So, I click the "x" next to the download progress bar to stop it. It does. I then select the messages and delete them. I close Mail. I expected the mass download to resume again when I opened Mail and it checked for new messages. It didn't. Of course now I figure it will pop up again even if it seems "fixed".
I haven't tried completely deleting that account and then adding it back yet. From what I've read elsewhere, I think if I do that the messages associated with that account will get deleted from the local database. I think I can move them to a Mail folder in the "On My Mac" category first and then delete the account to retain them (I want to retain the flagged, reply, forward etc tags I have on those messages). Similarly, I think I'd have to do the same (move the messages into a folder) if I want to temporarily disable the account in Mail until a patch comes out (Preferences > Accounts > POP Account > Uncheck "Enable this account".
I agree with Peter up there...it seems to be a problem when my iphone is checking it at the same time as my apple mail.
Before I upgraded to SL, I had a similar problem with Leopard mail while traveling once. The hotel wifi was one that you had to go to a landing page and put in your login details before connecting. It seemed that if mail was opened and tried to check for mail after I connected to the wifi, but before I connected to the net, it would download all of my messages over again.
The major difference in these two problems, was that before I could click the 'x' to stop the download and when I tried to check my mail it would continue downloading everything! Now it seems that when I click the 'x' it stops downloading and only downloads new messages, as it should, when it checks for mail.
Irritating problem nonetheless! I have 30k+ emails and don't enjoy them all getting downloaded over and over if I'm not there to stop it!
I've tried the solution of forcing the reload of the deleted messages file, but it only worked until the next time both my mac and iphone checked for mail at the same time.
I have been keeping two computers (one running Tiger and one running Snow Leopard) checking all my accounts, including several POP. No problems have arisen, as yet. This corrupting of the safeguards to prevent duplicate downloads must be limited to certain servers. But not a good thing!
My Testing has only been with Comcast because I converted all of my email accounts that were hosted by Godaddy to IMAP. Previously however, it did NOT occur with GoDaddy Servers.
Sometimes it would take three days for the duplicate email problem to occur with Comcast POP accounts.
I think you are correct; it is limited to certain servers
Once-upon-a-time Comcast was bad to corrupt the MessageUidsAlreadyDownloaded files, but in those days it usually resulted in no messages getting downloaded, and "stuck" messages on the Comcast servers. Those experiences did not require multiple computers or devices checking. Haven't seen that in a long time, but curious for this to be with Comcast.
It may happen with multiple clients accessing the same account (as reported), but it can also happen if there is only one. I only have the desktop email configured (no other email clients, no PDAs, no cell phone, etc), and it still occurs (at random intervals and not with every email).
