Summary: In this guide, we will talk about what is the standard Zimbra attachment size limit, ways to increase the limit by the administrator, common errors made by users, & best practices to prevent attachment size issue. Further, the safe and secure way to migrate Zimbra mailboxes with large attachments.
Talking about email attachments, they are used to share information with other recipients in terms of documents, presentations, images, through the mail system. But most of the administrators and users face problems related to limitations while sending or receiving large mails in Zimbra.
What is the Zimbra Attachment Size Limit?
Zimbra mail attachment size limit means the maximum size of an email message which includes your attachments and email itself. It is applicable to both sent and received emails in Zimbra Mail Server. The maximum value depends on:
- Global configuration of the server
- User configuration or class of service settings
- Maximum SMTP message size
- MIME encoding overheads
- Limitations of the mail client
By default, the Zimbra mail client sets the value of 10 MB as the maximum global message size. However, your administrator can increase the limit.
Also Read: How to Access Zimbra Webmail?
How Does Zimbra Calculate Attachment Size?
Most users think that only the attachment which they are inserting is counted. However, the actual total size of an email consists of:
- Email body
- The attachment itself
- Images within an email
- Extra space for MIME/Base64 encoding
- Email headers
Since attachments are encoded first before they are sent, even a 20 MB file could exceed the set limit for a server.
Common Zimbra Attachment Size Limit Errors
When the attachment exceeds the allowed limit, there can be:
- Message rejected by server
- Email in Outbox not sending
- “Message Size Exceeds Fixed Limit” SMTP error
- There can be upload problems
- Not able to receive large emails
- Migration process will skip large files
- You may face sync-related issue
Such problems happen most often when you migrate or take backup of your mailboxes.
Default Zimbra Mail Attachment Size Limit
The default settings normally consist of:
- Global Message Size – 10 MB
- File Preview Size – 20 MB
- Migration Upload Size – 10 MB
These settings depend on the Zimbra version you are using.
Why Does Zimbra Limit Attachment Size?
Attachment limits will help the administrators in the following ways:
- To maintain mail server performance
- Prevent misuse of storage
- Reduce bandwidth usage
- Speed up the mail delivery
- Decrease server crashes
- Avoid too many emails in SMTP queue
- Ensure security from malicious large attachments
Otherwise, having large attachments in bulk might affect server performance.
How to Increase Zimbra Attachment Size Limit?
Admins can extend the Zimbra attachment size limit by adjusting its server parameters. Follow the steps below to increase:
Step 1. Evaluate the current maximum size of the message on the server.
Step 2. Set the new message size quota on the server (zimbraMtaMaxMessageSize).
Step 3. However, with recent versions of Zimbra, you can define the size of attachments.
Step 4. It is allowed for particular users or Classes of Service through zimbraMailAttachmentMaxSize.
Step 5. After making changes in the configuration settings, you can test if email delivery works by sending a test email.
Best Practices to Follow:
Before increasing the maximum attachment size for Zimbra emails, you can consider the following points:
- Increase limits slowly
- Always take a look at your disk space
- Check that you have enough server memory
- Look at internet speed
- Evaluate SMTP relay limits
- Do not increase limits excessively
- Promote cloud sharing for very large attachments
Issue Faced while Migrating Large Attachments
Users commonly experience the following problems while they move their Zimbra TGZ mailboxes to other platforms.
- Big mailbox sizes
- Large attachments
- Upload limitations
- Damaged mailboxes
- Incomplete transfers
- Import failures
Securely Migrate Zimbra Mailboxes with Our Expert Software
If you have problems with the Zimbra attachment size limit, then don’t worry! Many people have to deal with that issue due to large email attachments which does not open properly. Although changing the settings of the server could solve the problem. If you want to transfer huge mailboxes of Zimbra to another email client, then SysTools Zimbra Converter software can simplify the migration process.
It safely converts TGZ emails along with all the attachments present in the mailbox. It retains the same folder hierarchy and metadata and allows users to convert to other formats like PST, EML, MBOX, PDF, and much more!
Key Features:
- It preserve large email attachments without changing the folder structure
- You can do bulk conversion of emails
- Retains email metadata such as To, From, Subject, Date, and attachments
- Provides selective conversion option
- Compatible with all major Windows versions
Software Steps to Convert Zimbra Emails to Popular Formats
1. Download & Install the professional software on your system.
2. To import the Zimbra mails, you need to select the Add File/Folder button.
3. Choose TGZ as the source file.
4. Once you import the data, you can preview your content.
5. It is possible to move your data using either of the two methods: one being the export of data or from selected files.
6. Select PST as your output format.
7. Tap on Advanced Settings to exclude some files and folders.
8. Click on Export in order to start the export process.
9. Finally, click on Save.
Tips to Avoid Zimbra Attachment Size Limit Issue
- You can compress the large files
- Divide the attachments into separate emails
- Delete any unused embedded images
- Archive your old attachments
- Use cloud storage links for oversize files
- Check your mailbox quotas frequently
- Maintain the latest server configuration
Conclusion
It is important to understand the Zimbra attachment size limit, since it helps to ensure effective email communication without any failures. The email content, encoding, and attachments are considered when measuring email size. Administrators should carefully set up limits according to the business needs and storage capacity. If you are moving your account from Zimbra, then doing it manually is quite difficult. For this purpose, our professional solution is best to migrate Zimbra mailbox data.
