How to Limit Email Attachment Size for Individual Users in Zimbra

Starting from Zimbra 10.1.6, Zimbra introduced the ability to limit attachment size per user. However, this feature is only available when using Webmail, Zimbra Desktop, or the Zimbra Connector for Outlook. If you are using an email client like Thunderbird, the maximum email size will follow the value set in the Global Settings.

Here is the configuration:

# Configure the setting directly on the user account

Admin Console → Home → Manage → Accounts → [User] → Preferences → Composing Email → Maximum message size (MB)

# Configure the setting on COS:

Admin Console → Home → Configure → COS → [COS] → Preferences → Composing Email → Maximum message size (MB)

The maximum size in this field must not exceed the value set inConfigure → Global Settings → MTA → Maximum message size

If you upload an attachment that exceeds the maximum message size per user, Zimbra will convert the attachment into a briefcase link with a random name.

Good Luck 🙂