Relay Email from External Infrastructure Through Kolab Now
Knowledge Base > Documentation > Relay Email from External Infrastructure Through Kolab Now
By Jeroen van Meeuwen on July 17, 2018

John Doe has a Kolab Now group manager account, and runs additional infrastructure — such as for a website or other application servers.

This article outlines how to ensure email is accepted for relay through Kolab Now, by using an authenticated relay configuration in the Mail Transfer Agent (MTA) of the sending system.

Relaying All Mail Through Kolab Now

This segment relays all mail going through the system’s MTA through the Kolab Now infrastructure.

Create a file /etc/postfix/relay-credentials and ensure the permissions are restrictive. Example contents are as follows; someone@domain.tld:password

Create a hash db mail from this file:

# postmap /etc/postfix/relay-credentials

Add the following configuration to /etc/postfix/

relayhost = []:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/relay-credentials
smtp_sasl_security_options =
smtp_tls_security_level = encrypt

Finally, restart the Postfix service:

# systemctl restart postfix

NOTE: The account for which the credentials are used must be allowed to use the sender address used in the emails. For example, if the credentials used are for, and mails are sent out using an envelope sender address of, then must have been allowed to send email using the sender address (using an alias or through delegation).

Configuring Specific Applications to Use Kolab Now

If specific applications allow configuration of the SMTP server address, port, TLS security settings and username and password to be used, then see the Generic IMAP Client Setup Guide for the configuration details.