My goal is to have a working offline copy of my email database on my phone, in case of no internet.

I know we can just go to Fetch Mail settings, choose:

• All mails for the Mailbox size

• Sync period to All time

But it is not as simple as that. For my case, I have around 200k emails. Using the above settings, Thunderbird would not even start to sync. The progress bar showed for like 5 seconds then hang. I made sure to check Cache / Storage size of Thunderbird after like 30 mins to see if it grows.. nothing happens.

Anyone managed to do this successfully?

Note: I also tried Fairmail and got even WORSE results than Thunderbird. Nothing against Fairmail, I love how advanced the settings are. But it just would not work reliably if you have a lot of emails. For comparison, I tried to fetch like 10k emails on both Fairmail and Thunderbird. After both finjshed downloading:

• Thunderbird: i can go Airplane mode, pick any emails and ALL contents are shown instantly. e.g. texts, attachments

• Fairmail: Airplane mode on, pick any emails and some emails are shown correctly, some are missing body texts and some just hang.

Never had your specific use case, but heard good things about K9 Mail?

They have a bulk export function, I did that. If you code you could probably do something with it to import somewhere else.

I don't know about Tbird on Android, but I can tell you: For a good while now, almost everything uses IMAP for email, which is generally better these days because it leaves everything on the server, and that's what most people want.

What you want is POP3, BUT you'll need ot make sure there's a setting to leave email on the server.

IMAP is designed to use email left on the server. POP3 is used to download (and remove) email from the server. But you want to also leave it on the server. But you want to use POP3 because it's designed to download all your email.

I don't think TB for Android can survive this. TB for PC works. It's able to deal with all my email dating back to 2006.

(sorry mostly for op but wanted to add to this comment) While I'm not much into email structure for imap tech, that does appear to be my experience. You can pull what it has but also need to make sure your saved is not more than what is allowed by provider. Full email does happen.

Unsure about the pop3 recommendation (never saves on server you just download it and it's gone from there but I probably missed something) but the forever for your syncing off IMAP was because you must have tons of shit in your email. Between the connection of your phone to internet vs provider it just took that long

If you let it properly sync once it'll probably be fine going forward. Just let it sync at the start of an evening or before a movie sort of thing and it'll catch up. But given what you said I'd do it on WiFi cause mobile data can be pricey is all. Though I get tons of data on my plan and rarely use it, good to know when you're using it elsewhere. Also most phones let you get an idea of mobile data vs WiFi to keep track if you're worried (android myself but mostly under settings, network .... Then somewhere underneath will let you know if you're getting too high)

Though guess if issue is your phone may not have space for it all, gotta work with that first. Can't suggest much than delete stuff you don't need. Sort of your own thing there unfortunately, rather than a strict suggestion.

Just figured I'd cover most bases for this issue. Also I was never paid well for tech support glad not my thing now but I so like attempting to help out.

Unsure about the pop3 recommendation (never saves on server you just download it and it’s gone from there but I probably missed something)

Covered:

What you want is POP3, BUT you’ll need ot make sure there’s a setting to leave email on the server.

I am speaking as someone who did helpdesk in the 1990s. :)

K9 on Android is now Thunderbird for Android. Aside from the older app versions, of course.

You could try your luck with a feature request in Thunderbird but the reality is that's probably not something most people want. Hardware manufacturers have successfully made on-device storage wildly expensive.

Aah thanks for clarifying that! I somehow missed that.

IMAP on desktop Thunderbird works. Or used to, you can never know these days.

Have you considered contacting FairEmail Support about your issue? Perhaps, the developer can help.