[MlMt] Updating account information made MailMate (re)download *all* email

[Sherif Soliman]

On 1 Aug 2016, at 6:01, Benny Kjær Nielsen wrote:

> On 28 Jul 2016, at 2:37, Sherif Soliman wrote:
>
> [FastMail issues]
>
>> What I chose to do is to start with a fresh install of MailMate. I 
>> kept a copy of my keybindings file and `Tags.plist`, removed 
>> everything else, and set everything up from scratch. I haven't had 
>> any issues since.
>
> I'm glad it works given that I didn't provide much help. Thanks for 
> the updates (and warning for other users).
>
> Now, I'll try to analyze what happened.
>
> You wrote:
>
>> I put in the new password and changed the server names from the old 
>> `mail.messagingengine.com` to `<protocol>.fastmail.com`.
>
> I'm pretty sure MailMate displays a warning at this point. This is 
> because you have to be absolutely sure that MailMate is still looking 
> at the exact same account. Otherwise, the mapping between local emails 
> and server emails might be incorrect which could, e.g., lead to 
> deleting a message locally which maps to a different message on the 
> server. (This is not very likely to happen due to what follows below, 
> but some servers have a somewhat primitive use of `UIDVALIDITY` often 
> reusing values between user accounts.)
>

Yes, I remember seeing that warning. I read its meaning as you just 
described it: make sure this is the same account as it was before 
because if MailMate authenticates and finds different messages than what 
it had before, it will download them and delete the old ones, and 
generally do whatever it needs to do to reflect the new reality it finds 
on that server.

> Now, it looks like this should be ok with FastMail, but then it seems 
> something else happened. The redownloading of emails indicate that the 
> `UIDVALIDITY` value changed of each mailbox. Each email is uniquely 
> identified using the `UIDVALIDITY` of the mailbox and the `UID` of the 
> message. If the `UIDVALIDITY` value of a mailbox changes then MailMate 
> MUST delete its local cache of emails and then fetch the “new” 
> messages of the mailbox. There is no way to tell MailMate to ignore 
> `UIDVALIDITY` changes.
>
> Hmm, MailMate should also warn you when the latter happens which makes 
> me think that this might be a MailMate bug after all. I have a 
> FastMail test account and I'll note to test what happens when I do as 
> you describe. Sorry about the inconvenience if this turns out to be a 
> bug.
>

I did not see any other warnings besides that first one.

Sherif