Put it on hold
sudo apt-mark hold

Remove from hold
sudo apt-mark unhold

Test nextcloud ldap connection
std should be list of ldap users

curl -v -X GET -u 'username:password' https://nextcloud.url/ocs/v2.php/cloud/users -H "OCS-APIRequest: true"

dig -t txt dkim._domainkey.domain.tld

Quick hack on how to set certificates right on iRedmail

To begin with:
jmx concole - jconsole (part of jdk package)

Notes written after a full iredmail app recovery

System setup:
Debian 9 Stretch, MariaDB, Iredmail v0.9.9, iRedAdmin v0.9.3 (LDAP), Nginx, Lets encrypt, Icinga2

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USEFUL ONE-LINE SCRIPTS FOR SED (Unix stream editor) Dec. 29, 2005
Compiled by Eric Pement - pemente[at]northpark[dot]edu version 5.5

Check owncloud ldap stats via OCC
./occ ldap:show-config

Usually runs under www user
sudo -u www-data ./occ ldap:show-config

gitlab-ctl reconfigure
gitlab-ctl start
gitlab-ctl stop