Upgrade and downgrade instructions
To upgrade MailerQ from version < 5.6 to 5.6+
Debian/Ubuntu:
sudo apt update
sudo apt install -y mailerq
sudo mailerq --repair-database
CentOS/RHEL:
yum update
mailerq --repair-database
To downgrade MailerQ from version 5.6+ to 5.5
Debian/Ubuntu:
sudo apt-get install -y --allow-downgrades mailerq-5.5
sudo mailerq --repair-database
CentOS/RHEL:
yum remove mailerq-5.6
yum install mailerq-5.5
mailerq --repair-database