Configuring maxmessagesize

Revision as of 16:29, 15 January 2013 by Ajcody (talk | contribs) (Initial Warning)

The following explains how to observe and adjust the Maximum Message Size for messages passing through the Zimbra MTA (Postfix). The message_size_limit postconf parameter is configured globally for all Zimbra MTAs. The default Zimbra MTA configuration uses the default Postfix message_size_limit of 10MB (i.e. '10240000' bytes). Note that this is the size of the full RFC 2822 internet message, after any necessary MIME-encoding.

An Initial Warning On These Values

Please do not set these limits too high, as postfix will check to confirm you have the free space on the partition. For zimbraMtaMaxMessageSize, it multiplies the variable by 1.5 and if the free space isn't available on the partition it will not send ANY messages - effectively causing an mta outage. You'll see a message in /var/log/zimbra.log like this if you set zimbraMtaMaxMessageSize to high :

Jan 15 11:18:53 SERVERNAME postfix/smtpd[29088]: NOQUEUE: reject: MAIL from[]: 
  452 4.3.1 Insufficient system storage; proto=ESMTP helo=<>
Jan 15 11:18:53 SERVERNAME postfix/smtpd[29088]: warning: not enough free space in mail queue: 
  161044520960 bytes < 1.5*message size limit

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 2048000
$ postfix reload

You can then confirm the changes with this command:

$ postconf | grep message_size_limit

File upload size configuration (zimbraFileUploadMaxSize)

Until ZCS 5, there is a separate configuration parameter for file uploads . File uploads include, for example, attachments to messages (appointments, tasks, etc), and messages imported by the migration tools (PST Import Wizard, Exchange Migration Wizard, etc). The zimbraFileUploadMaxSize can be configured globally or per server. Note: If you have more than one mailbox node, it may be necessary to restart tomcat on nodes where the commands were not run in order to pick up the changes immediately.

This will globally set the size to 5mb:

# su - zimbra
$ zmprov modifyConfig zimbraFileUploadMaxSize 5000000

Then this will allow 20mb uploads to the server

$ zmprov modifyServer zimbraFileUploadMaxSize 20000000

The size of the zimbraMailContentMaxSize controls the overall message size

su - zimbra
zmprov ms `zmhostname` zimbraMailContentMaxSize 20000000  
zmprov modifyConfig zimbraMailContentMaxSize 20000000
<attr id="807" name="zimbraMailContentMaxSize" type="long" cardinality="single" optionalIn="globalConfig,server" flags="serverInherited" since="6.0.0_BETA1">
  <desc>Maximum size in bytes for the <content > element in SOAP.  Mail content larger than this limit will be truncated.</desc>
 Here is an example to set the max message size to 42MB
zmprov ms `zmhostname` zimbraFileUploadMaxSize 44040192
zmprov ms `zmhostname` zimbraMailContentMaxSize 44040192
zmprov mcf zimbraMtaMaxMessageSize 44040192
postfix reload
one thing to watch for is to use a conversion toll to calculate the value in bytes otherwise it won't be accepted

Additional Resources

Verified Against: unknown Date Created: 1/31/2007
Article ID: Date Modified: 2013-01-15

Try Zimbra

Try Zimbra Collaboration with a 60-day free trial.
Get it now »

Want to get involved?

You can contribute in the Community, Wiki, Code, or development of Zimlets.
Find out more. »

Looking for a Video?

Visit our YouTube channel to get the latest webinars, technology news, product overviews, and so much more.
Go to the YouTube channel »

Jump to: navigation, search