Here is how to restrict users to send emails to certain domains in the Zimbra mail server. 1. Open file /opt/zimbra/conf/zmconfigd/smtpd_recipient_restrictions.cf and add this line: check_sender_access lmdb:/opt/zimbra/conf/restricted_senders 2...
Back in 2018 CloudFlare reported massive amplification attacks from UDP port 11211 on a scale never seen before. Zimbra quickly updated their wiki with How to Block Memcache Attack and if you haven’t taken the advice yet, you probably should...
Recently I was tasked to install a free SSL certificate from LetsEncrypt on a local Linux machine that was running Zimbra Mail Server. The task seemed simple, and I had no problem generating and installing the certificate from LetsEncrypt on Linux...
To redirect HTTP to HTTPS, switch to zimbra user:
su - zimbra
then run:
zmprov ms SERVER_HOSTNAME zimbraReverseProxyMailMode redirect
that’s it!