[MlMt] Exclude from Backup / Time Machine

[Bill Cole]

On 2023-09-14 at 07:56:03 UTC-0400 (Thu, 14 Sep 2023 13:56:03 +0200)
Michael Nietzold <mailmate at lists.freron.com>
is rumored to have said:

> I'm trying to determine which folders I can safely exclude from a Time 
> Machine backup...
>
> I haven't been able to locate any official documentation on this. I've 
> come across some messages on the mailing list, but they don't offer 
> clear advice either.
>
> I would expect an info in this section of the MailMate Manual: 
> https://manual.mailmate-app.com/rebuild
>
> Below are my current directories...
>
> - Are there any other important directories located elsewhere?

Everything specific to MM is in ~/Library/Application Support/MailMate 
except for a .plist file in ~/Library/Preferences/

> - Is it safe to exclude both Messages.noindex/ and Messages/?

Since Messages/ is just a symbolic link to Messages.noindex/, you don't 
need to be concerned with it.

You are probably good with excluding Messages.noindex/ because in 
principle it is just a copy of messages on your various accounts' IMAP 
servers. In principle, you can recover all of your messages by 
downloading them all again. In practice, that is not only viable, it is 
likely to be faster than restoring from TimeMachine, which is 
spectacularly slow. It is also relatively slow to back up because of the 
interaction between its storage model and how TM does incremental 
backup.

> - Additionally, I've heard suggestions about excluding 
> Database.noindex/. Would this be advisable?

Yes. It is huge and constantly in flux with some very large files 
getting small changes every time a message is retrieved or deleted. If 
you do not back up Messages and rely on your IMAP servers in  the event 
of needing a restore,  the Database folder (which contains all of the 
indexing MM uses for search) would be entirely rebuilt anyway as 
messages are retrieved. I suspect (but only Benny could confirm) that 
even if you backed up both Messages and Database, the restore from TM 
would not work due to file->inode mapping being changed. (arcane 
technical issue...) It is my belief that if you did restore both the 
messages and their index together, MM would ask at startup how you want 
to rebuild the database (from local messages or re-fetch.)

The TL;DR version: I exclude both of the big directories and have never 
regretted it. Restore from IMAP works and unless you have a huge mailbox 
on a rate-limited server (e.g. freebie GMail) it is adequately fast.



-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire