Berikut ini adalah cara install dovecot versi 2.3 di centos 6 dan 7.

Buatlah /etc/yum.repos.d/dovecot.repo

[dovecot-2.3-latest]
name=Dovecot 2.3 CentOS $releasever - $basearch
baseurl=http://repo.dovecot.org/ce-2.3-latest/centos/$releasever/RPMS/$basearch
gpgkey=https://repo.dovecot.org/DOVECOT-REPO-GPG
gpgcheck=1
enabled=1

If you are upgrading an existing installation

yum makecache
yum update

Sumber : https://repo.dovecot.org