Is this normal ? did I find a bug ?

You're correct, it's indeed a bug of recent iRedMail releases. Fixed moment ago, will releasae iRedMail-1.8.4 with this fix shortly:
https://github.com/iredmail/iRedMail/co … 3dedd2f347

By the way:
- iRedMail Enterprise Edition ("EE") is not affected.
- If you upgraded Debian from 12 to 13 by following our tutorial[1], it's not affected[2] either.

[1] https://docs.iredmail.org/upgrade.debian.12-13.html
[2] https://github.com/iredmail/docs/blob/m … .conf#L727

A fresh install on debian 13, then restore config and data

This is the error we get :

dovecot: sieve(name@domaine.tld)<16329><mBy5ACZXnsB/AAAB>: Error: sieve: file storage: Sieve storage path '/var/vmail/vmail1/domaine.tld/n/a/m/name-
2021.04.15.10.29.46//sieve/dovecot.sieve' is not a directory, but it is to be opened for write access 

To solve this problem we had to change dovecot.conf from this :

sieve_script personal {
    type = personal
    driver = file
    path = ~/sieve/dovecot.sieve
}

to this :

sieve_script personal {
    type = personal
    driver = file
    path = ~/sieve
    active_path = ~/sieve/dovecot.sieve
}

It's the second server on debian 13 that has this issue.

Is this normal ? did I find a bug ?