Periods (".") not allowed in email folder names, maildir change needed

[guyds]

While trying to migrate an email account from another mail system to Cloudron I noticed that it doesn't succeed because folders have a "." (period) in their name and maildir uses a "." to separate subfolders on the filesystem.

This can easily be solved by adding LAYOUT=fs to the mail_location option in the config file, but I'm not sure where I can do this in Cloudron?
Can anyone point me to the correct location to make this change?

Also, if I make this change, will it persist after upgrades?

The documentation for this setting can be found at the Dovecot website.
And for a more in depth read on the matter of periods and slashes in mail folders you should take a look at this post.

[girish]

Currently, the mail server does not allow this to be customized. Is it possible to rename the original folders and then import it?

We set this as mail_location = maildir:~/mail . Changing this will break most people's imports since this is the dovecot default. Using FS has other complications wrt naming of new/cur directories (listed in the link you posted). Generally, we tend to not allow these complicated settings to be customized since it's much work to test them.

[guyds]

Well, the thing is that I can obviously rename folders in my own account(s) in order to work around this, but when migrating accounts for other family members, colleagues or clients it's harder since I will be asking them to change their folder naming habits just because the mailsystem can't handle it.

To be honest I never ran into this with other mailsystems and I've used / tried a considerable amount of them in the meantime: Google (Gmail/workspace), Microsoft (hotmail/365), Zoho, Mailcow just to name a few and they all accept periods in folder names.
As a result we got used to use periods in our folder names.

I'm fine if the default stays as it is in order to not break anything for other people, but being able to change it when needed would be nice.
And yes, there are possible collisions with the internal folders (new, cur, tmp) when switching to FS, but this can be anticipated by setting the DIRNAME variable to something unique.

In regards with testing, I'm not sure this has a huge impact since the working of dovecot shouldn't change in any way when switching to FS.