Email size limits explained

This guide explains the two size limits that affect your email: how big one message can be, and how much a mailbox can hold.

Attachment size

Every email server sets a largest message size it will accept. If your message is bigger than that, it bounces back to you, usually with a message saying it is too large.

The limit that matters most is often the one at the other end. Many large email providers reject messages over about 25 MB, and some business systems set a much lower limit. Your message has to fit every server it passes through.

Why a 20 MB file can be too big

When a file is attached to an email, it is converted into text so it can travel safely. This encoding makes it about a third bigger. So:

• a 15 MB file becomes about 20 MB in the email
• a 20 MB file becomes about 27 MB, which many providers will reject

As a rule, keep attachments under about 15 MB in total to be safe.

Mailbox quota

Each mailbox on your hosting has a quota, which is the most mail it can store. When it is full, new messages to that address bounce and the sender gets an error.

To check or change a quota:

1. Log in to cPanel.
2. Open Email Accounts.
3. Look at the storage used next to each address.
4. Click Manage next to an address to change its quota.

See how to change an email password or mailbox size for full steps. The space you give mailboxes comes out of your hosting account’s total storage.

Sending large files

For anything big, don’t attach it. Instead:

1. Upload the file to a file-sharing service such as OneDrive, Google Drive, Dropbox or WeTransfer.
2. Create a share link.
3. Paste the link into your email.

This also keeps your Sent folder from filling up, and the person you’re sending to won’t hit their own quota.

If it doesn’t work

• Your message bounces with “too large” or “size exceeded”. Send the file as a link, or split it across several emails.
• People say their email to you bounced. Your mailbox may be full. Check the quota in cPanel, delete old mail or empty the trash, or raise the quota.
• Your mailbox fills up quickly. Look in Sent and Trash, which often hold old attachments. Deleting them in webmail or your mail app frees the space.
• You need to know the exact sending limit on our servers. Open a ticket and we’ll confirm it for your account.

Good to know

If mail isn’t going out for another reason, see why is my email not sending.

Still stuck? Open a support ticket and we’ll help.