Are you looking for how to change the Zimbra message size limit?

It is quite easy to change the global Zimbra parameters to alter default size limits on messages.

At Bobcares, we often change the size of the message passing through Zimbra MTA, as a part of our Server Management Services.

Today, we will see how our Support Engineers do this for our customers.

A brief look onto Zimbra MTA

The Zimbra Mail Transfer Agent receives mail via SMTP. It routes the message, using the Local Mail Transfer Protocol to the Zimbra mailbox server.

The Zimbra MTA server includes Postfix, ClamAV, SpamAssassin, and Amavisd. It uses Postfix MTA for mail routing, relaying and blocking attachment.

Many of our customers approach us to change the default size limit on the mails. Let us see how we do it.

How we change the default Zimbra message size limit?

The total mail content size consists of both message size and file content size. But, we can change this value by changing the required parameters.

Firstly, our Support Engineers check the already existing value. For this, we get into the Zimbra console using the command,

su - zimbra

Later we check the message_size_limit and the result appears as,

To change this value we have to edit the zmmtaconfig file. But we can invoke this using commands. The command to change the message size limit appears as,

zmprov modifyConfig zimbraMtaMaxMessageSize 20480000
postfix reload

And this changes the default value to 20MB. But this alone does not determine the mail size. So let us see how our Support Engineers change the related parameter.

Other related parameters

So, we change the file upload size also. We either give a global value or give separate value per server. To set the global value we use the command,

zmprov modifyConfig zimbraFileUploadMaxSize 5000000

To set a particular file upload size for the server, we use the command,

zmprov modifyServer mail.domain.com zimbraFileUploadMaxSize 20000000

Here the file upload size just applies to mail.domain.com.

But, the zimbraMailContentMaxSize determines the overall message size. And we change the default parameter as follows,

zmprov modifyConfig zimbraMailContentMaxSize 20000000

Hence all these parameters together determine the total size of a mail passed through Zimbra.

[Need assistance in fixing Zimbra MTA errors? – We are available 24/7.]

Conclusion

In short, the Zimbra message size limit together with file upload size determines the total size of the mail. To change these parameters we can either edit the Zimbra config file or invoke it using commands. Today, we saw how our Support Engineers do this.