Gmail stopped downloading; can redownload all mail but just want new items

Question

Yesterday Mail stopped downloading my e-mail from Gmail via POP. Looking at an old forum post, I saw a suggestion from someone to try deleting MessageUidsAlreadyDownloaded2 from the ~/Library/Mail/[account]/ folder. Doing so causes Mail to start downloading my mail from Gmail starting with the first message in my Gmail account, a process that would take days to complete. I tried to edit the file, but it doesn't really make sense to me. All of the "DateDownloaded" keys seem to have a value of sometime (different times) in February 2006. I tried leaving only one of them (I tried both the first key/value pair and the last), but that just started downloading from the beginning also.
Is there any way to get Mail to download messages only after x date, or to somehow fix whatever is wrong with my record of Uids Downloaded?
Thank you for any help you can provide,
Greg

Answer 1

If I remove the file again, it will start downloading not after the
point where it had left off, but again at the very beginning.
Does Mail actually complete the download or does it stall at some point? I mean, what may be happening here is that Gmail doesn’t mark those messages as already downloaded because Mail doesn’t complete the transaction.
The presence of MessageUidsAlreadyDownloaded2 can certainly make a difference for messages that Gmail hasn’t marked as already downloaded for some reason or if there is something wrong with that file, but there is no way the presence of that file could have an impact on messages that had successfully been downloaded in a completed transaction.
I have connected from multiple devices, as I stated before.
Well, you talked about “programs”, not “devices”. Note that in the list of idiosyncrasies that you don’t find useful I talk about “conventional POP mail clients”. Some handheld devices appear to not be affected by this.
The inability to download a message to a computer more than once is actually a “feature” documented here:
What happens to messages stored on Gmail's servers?
The ability to download messages on multiple devices is documented here:
How should I use POP on mobile or multiple devices?
I am neither an incompetent computer user nor someone fabricating
this wacky e-mail story just for kicks.
Nor have I ever thought that was the case, but knowing how Gmail works, I do know that some of the things you said had to be necessarily wrong.
In particular, in the case of a Gmail account, there is no way removing MessageUidsAlreadyDownloaded2 from the account folder might cause Mail to start downloading everything from the server again after having successfully done that at least once. The only way that might happen is if you had also selected Enable POP for all mail in Gmail’s Settings > Forwarding and POP page, which you haven’t mentioned at all in any of your posts.
While you keep saying that you understand how Gmail works, the fact is that some of the things you’ve said are wrong, and you’ve ignored/omitted essential information about the things you’ve done that clearly indicate you don’t fully understand how Gmail POP access really works. I’m sorry if telling you that offends you, but I must do so in order to be able to help you...