Oh...seems my local master I branched off was before your changes were merged, I'll rebase to get all that (EDIT: Nope apparently I misunderstood the extras).

I intentionally didn't use upper case as they're local vars, I'm used to uppercase for constants or ENV vars, but if the code style has changed to that I'll adopt it.

I did glimpse this from current upstream master:

https://github.com/tomav/docker-mailserver/blob/a0c2dc27c8cb75ef97308c3234945f26e116fa33/target/start-mailserver.sh#L680

      # Setting variables for better readability
      user=$(echo "${login}" | cut -d @ -f1)
      domain=$(echo "${login}" | cut -d @ -f2)

      user_attributes=""

# ...

IFS=':' ; read -r -a USER_QUOTA < <(grep "${user}@${domain}:" -i /tmp/docker-mailserver/dovecot-quotas.cf)

# ...

echo "${login} ${domain}/${user}/" >> /etc/postfix/vmailbox

Were these missed or are they lowercase globals? (they're not declared with local scope, I'm not that experienced with shell/bash, so I might be misunderstanding what's going on there conventions wise)

There are many inconsistencies left in start-mailserver.sh even after my refactoring. You just showed an example. But: The variables are also present in check-for-change.sh. If we rename them, we should do it consistent across the board. I just refactored what you introduced with your PR however. There is more work to make this huge script 100% consistent.

PS: We (with the new styling guide) don't differentiate between the scope of the variables when naming them, i.e. they are always just uppercase. The local keyword does that for us:)

Ok, no problem. The user-patches addition is to sync with your recent commit to upstream master?

The spelling error with the regiter_functions() is to be reverted for CI trigger?

Ok, no problem. The user-patches addition is to sync with your recent commit to upstream master?

Correct. This is more or less a "leftover" from my master where I copied something from.

The spelling error with the regiter_functions() is to be reverted for CI trigger?

More or less. When I refactored, I was never quite sure where some error came from, for example the user quota error. Therefore it's best to isolate these causes and change the spelling in the end.

PS: If you want, you can make this:

      # Setting variables for better readability
      user=$(echo "${login}" | cut -d @ -f1)
      domain=$(echo "${login}" | cut -d @ -f2)

      user_attributes=""

# ...

IFS=':' ; read -r -a USER_QUOTA < <(grep "${user}@${domain}:" -i /tmp/docker-mailserver/dovecot-quotas.cf)

# ...

echo "${login} ${domain}/${user}/" >> /etc/postfix/vmailbox

more consistent, you should just rename it in check-for-changes.sh too. (Not sure whether they interfere)
You can see the diff for this on my fork of your repo on this exact branch.

PS: If you want, you can make this:

Sorry, I don't have the spare time to allocate to fixing code style(as much as I value consistency myself), I'm mostly interested in completing my main PR for the project(testing environment setup now, have run initial tests, now need to work through my checklist), possibly adding a bit more to the wiki and after a bit more polish publishing a repo or sending a PR of the docker-compose local TLS setup (CoreDNS for resolving FQDNs with mail records and ACME DNS challenges, smallstep's step-ca for private CA and ACME provisioner, acmebot for provisioning the certs via ACME, the mailserver and any tests like testssl.sh).

After all that, I have more on my backlog to wrap up elsewhere 😅

Of course, this was just an idea:) I will do this later :D