Oh, I just saw, that I mixed hostname/container name. I’ve edited my post.

I took mail from the posted docker-compose.yml above 😉

Which one? I can only see container_name: mailserver 😃

I think it’s not yet working.

DS918p:/volume1/docker/mailserver-edge$ sudo ./setup.sh email add test@example.com test
DS918p:/volume1/docker/mailserver-edge$ sudo ./setup.sh email del test@example.com
Do you want to delete the mailbox as well (removing all mails) ? [Y/n] y
Mailbox directory '/var/mail/example.com/test' did not exist.

I manually confirmed /var/mail/example.com/test exists. Also I was able to login to the test account using Roundcube and I made a draft message to test.

Also I expected pressing Enter in response to this question: Do you want to delete the mailbox as well (removing all mails) ? [Y/n] would go for the Y option since it’s capitalised. But it went with n instead and gave me this: Leaving the mailbox untouched. If you want to delete it at a later point use 'sudo docker exec mail rm -R /var/mail/example.com/test'.

Manually running sudo docker exec mail rm -R /var/mail/example.com/test was so far still the only way to actually remove the mailbox contents.

This:

#! /bin/bash

# ? This is done to ignore the message "Make sure not to read and write
# ? the same file in the same pipeline", which is a result of ${DATABASE}
# ? being used below. (This disables the message file-wide.)
# shellcheck disable=SC2094

# shellcheck source=../scripts/helper-functions.sh
. /usr/local/bin/helper-functions.sh

DATABASE=${DATABASE:-/tmp/docker-mailserver/postfix-accounts.cf}
ALIAS_DATABASE="/tmp/docker-mailserver/postfix-virtual.cf"
QUOTA_DATABASE="/tmp/docker-mailserver/dovecot-quotas.cf"

function usage
{
  echo "Usage: delmailuser [-y] <user@domain> <user2@anotherdomain> ..."
}

while getopts ":y" OPT
do
  case ${OPT} in
    y)
      MAILDEL="y"
      ;;
    \?)
      usage
      errex "Invalid option: -${OPTARG}"
      ;;
    *)
      usage
      errex "Invalid option: -${OPTARG}"
      ;;
  esac
done

shift $((OPTIND-1))

[[ -z ${*} ]] && { usage ; errex "No user specifed" ; }
[[ -s ${DATABASE} ]] || exit 0

(
  flock -e 200

  for USER in "${@}"
  do
    # very simple plausibility check
    [[ ${USER} != *'@'*'.'* ]] && errex "No valid address: ${USER}"

    declare -a MAILARR
    MAILARR[0]="${USER%@.*}"
    MAILARR[1]="${USER#.*@}"

    # ${USER} must not contain /s and other syntactic characters
    USER=$(escape "${USER}")

    if [[ -f ${DATABASE} ]]
    then
      if ! sed -i "/^""${USER}""|/d" "${DATABASE}"
      then
        errex "${USER} couldn't be deleted in ${DATABASE}. ${?}"
      fi
    fi

    if [[ -f ${ALIAS_DATABASE} ]]
    then
      # delete all aliases where the user is the only recipient( " ${USER$}" )
      # delete user only for all aliases that deliver to multiple recipients ( ",${USER}" "${USER,}" )
      if sed -i \
        -e "/ ""${USER}""$/d" -e "s/,""${USER}""//g" -e "s/""${USER}"",//g" \
        "${ALIAS_DATABASE}"
      then
        echo "${USER} and potential aliases deleted."
      else
        errex "Aliases for ${USER} couldn't be deleted in ${ALIAS_DATABASE}. ${?}"
      fi
    fi

    # remove quota directives
    if [[ -f ${QUOTA_DATABASE} ]]
    then
      if ! sed -i -e "/^${USER}:.*$/d" "${QUOTA_DATABASE}"
      then
        errex "Quota for ${USER} couldn't be deleted in ${QUOTA_DATABASE}. ${?}"
      fi
    fi

    if [[ ${MAILDEL} != "y" ]]
    then
      read -r -p "Do you want to delete the mailbox as well(all mails will be removed)?(y/n) " MAILDEL
    fi

    if [[ ${MAILDEL} != "y" ]]
    then
      echo "Leaving the mailbox untouched. If you want to delete it at a later point use 'sudo docker exec mail rm -R /var/mail/${MAILARR[1]}/${MAILARR[0]}'"
      exit 0
    fi

    if [[ -d "/var/mail/${MAILARR[1]}/${MAILARR[0]}" ]]
    then
      if rm -r -f "/var/mail/${MAILARR[1]}/${MAILARR[0]}"
      then
        echo "Mailbox deleted."
      else
        errex "Mailbox couldn't be deleted: ${?}"
      fi
    else
      errex "Mailbox directory '/var/mail/${MAILARR[1]}/${MAILARR[0]}' does not exist."
    fi
  done

) 200< "${DATABASE}"

is my refactoring. Seems a lot cleaner and more robust to me.