Increasing Attachment size in Zimbra

For increasing size of attachments to 50 MB in Zimbra, a few settings need to be altered as follows:

Postfix configuration (zimbraMtaMaxMessageSize and message_size_limit)
You can examine the current value of this parameter like this:

# su - zimbra
$ postconf message_size_limit
message_size_limit = 10240000

This configuration parameter is stored in the zimbra ldap directory, and propagated to postconf’s message_size_limit by zmmtaconfig, which is invoked by the zimbra postfix command. The following commands will set the message_size_limit to 2MB (adjust this value to suit your needs):

# su - zimbra
$ zmprov modifyConfig zimbraMtaMaxMessageSize 52428800
$ postfix reload

You can then confirm the changes with this command:

$ postconf | grep message_size_limit

Change the limits in Zimbra configuration for all types of files uploads.

$ zmprov modifyConfig zimbraFileUploadMaxSize 52428800
$ zmprov ms `zmhostname` zimbraMailContentMaxSize 52428800
$ zmcontrol restart