The sales manager says a customer sent an email and got an error back. You check and find their mailbox is full, so the server is bouncing new email. This usually creeps up quietly: “Your mailbox is almost full” warnings get ignored until the day an important email doesn’t arrive.
Why do mailboxes fill up?
- Large attachments: Design files, scanned documents and presentations sent back and forth many times.
- The Sent folder: Every attachment you send also leaves a copy in Sent.
- Trash and spam: Deleted messages take up space until these folders are emptied.
- Unnecessary copies: Group emails with attachments sent to dozens of people.
Step 1: See where the space is going
In webmail or the account settings, check the size of each folder. In Outlook, you can also find large messages using the folder size view and searching by message size. Usually a few folders and a handful of large messages take up most of the space, and dealing with those is enough.
Step 2: Smart cleanup
- Empty the trash and spam folders, or enable automatic deletion of messages older than a set period for these folders in the server settings.
- Save important attachments from large messages to the project folder on the file server, then delete the attachment or the whole message.
- Bulk-delete old newsletters and automated emails.
- Review old large messages in the Sent folder.
For large files, send a share link from the file server or the company’s cloud storage instead of an attachment. Neither your mailbox nor the recipient’s fills up, and everyone has access to the latest version of the file.
Step 3: Archive on the server, not on the laptop
A common but risky approach is an Outlook archive in a local file on the user’s computer. These files usually aren’t backed up, may become corrupted as they grow, and are lost if the laptop fails or goes missing. Archived emails also don’t show up on phones or in webmail.
A better approach is to archive on the server itself:
- Yearly archive folders: Messages from past years are moved to folders such as “Archive 2023” on the server. With IMAP, these folders are available on every device.
- Server-side archiving: Many business mail servers can automatically archive messages in a space separate from the user’s mailbox; exact features depend on the server version and license.
- Retention policy: Define how long each type of email must be kept. For financial and contractual email, review legal and internal company requirements with a legal or financial advisor.
Step 4: Quotas that match the role
Not every mailbox needs the same amount of space. The CEO’s mailbox, or those of the sales or procurement teams, usually need more space than that of a user with little correspondence. Set quotas by role, keep near-quota warnings enabled, and review a mailbox size report once a month. Also set limits on outgoing and incoming attachment size and tell users what they are.
Don’t forget backups
An archive is not a backup. If a message is deleted by mistake or a mailbox is damaged, only a regular mail server backup can bring it back. Make sure the mail server backup also covers archive folders, and that restoring a mailbox has been tested.
Checklist
- Mailbox sizes are reviewed monthly and quota warnings are enabled
- Trash and spam folders are emptied automatically
- Large files are sent as links, not attachments
- The archive is on the server, not in a local laptop file
- An email retention policy is defined
- The mail server backup includes the archive and has been tested
ITPlus724 engineers can design and implement mailbox quotas, server-side archiving and business email backup on SmarterMail for your company.