How to Show Message Sizes in Apple Mail

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Most email messages are small. Some have a reported size of 0 bytes, but exceptions exist. To spot larger messages immediately at once when you look at a mailbox in Apple's Mail app, you can include the message size in the list of displayed message attributes.

Instructions in this article apply to Mac OS X 10.11 and higher.

How to Show Message Sizes in Apple Mail

To display the message size in the Mail message list:

  1. Under the View menu, select Message Attributes and click Size.

    Size under Message Attributes in Apple Mail
  2. Now, the size of a message will appear under the date you received it.

    Message size in Mail
  3. To sort messages by size, select that option under the Sort By pulldown menu.

    Sort messages by size in Apple Mail
  4. You can also use this menu to decide whether to sort your messages in ascending order (smallest messages on top) or descending (largest messages first).

Why Would You Want to Know the Message Size?

You might want to know the message size in order to determine if a message has attachments or images within it. You might be looking for an especially long message or one with a lot of information or a large attachment. If your mailbox is full, you may want to delete these larger messages first in order to free up space on the mail server or to speed up the syncing of a new device.