Sounds like it should work, if you can get your apple devices to leave a connection for your pop account to use. They can be greedy and basically use up all available connection and lock out other applications, even at time other apple devices.

Still confused.

(1) what I describe above isn't going to get my sent mails on to the home machine (where I want to keep a permanent record, not let IMAP delete them after a year or whatever) -- is it?

(2) I've seen another solution to the situation: use IMAP everywhere, but on the machine you want to keep the permanent record, arrange to have the IMAP folders copied to local folders. I can't get my head around how that would work.

Thanks!

Personally I have (2): I use Thunderbird on my laptop but I also access my mail from a tablet and phone (tho Android rather than Apple). I guess there are two points to grasp: a) If you have a folder in your Thunderbird account and it is 'subscribed' to the server, then the same folder exists on the server and the content of the two folders are kept 'in sync'. If you use another device to subscribe to that folder on the server it will see the same messages that you see in Thunderbird. The standard Inbox, Sent, Deleted folders are subscribed by default but you can also create other folders to organise your mail as you want. If those other folders are also subscribed, then again other devices will be able to view and manage the content of them. b) If you have a folder in your Thunderbird account that is not subscribed, then the content of it is not kept on the server and cannot be accessed from other devices. The easiest way to achieve this is to create it under the 'Local Folders' account in Thunderbird. Messages kept there exist only on your machine, not on the mail server from which they came originally. Two other points to consider: - Although you can move or copy messages to local folders manually, you can also set up a 'message filter' in Thunderbird which will copy them automatically, or subject to certain conditions (e.g. messages only from certain recipients) - Once moved off the server you have no backup of those messages unless you maintain a safe copy of your Thunderbird profile. From time to time we get anguished messages in the forum from people who have lost all their saved mail because they downloaded it and then their computer failed. If you leave it in folders on the server you have that backup automatically.

How does a message filter from the Sent folder work? I only have experience with writing filters that look at mails coming to TB, not going from TB.

Yes, backup is always a serious issue. I use Time Machine and Dropbox: I've also given some thought to purchasing more space from Dropbox so I could just put my TB setup there.

One other puzzle about saving to local folders: if I'm at home at the "archival" machine, I get my mail with IMAP, and I do the usual reading, deleting etc. Now, if there's a filter that copies everything to local folders, then I'm going to have to delete stuff twice. So do I do the filtering semi-manually: when I'm satisfied that the day is done and there's no more deleting to happen, tell the filters to run?

I'm not the best person to help you with detailed questions about filters because I don't use them much. There's a general article here with links to further information: http://kb.mozillazine.org/Filters_%28Thunderbird%29 It also references an add-on, 'Send Filter', which operates when mail is sent. I can't advise about the optimum workflow for you. Can I suggest that if you want to explore the use of filters further, you start a separate thread about it? I took this thread to be mainly about whether to use IMAP or POP and I've tried to help with that; if you now want to learn about filters you're more likely to get help if the the thread title says so clearly.