Mail and Messages are polite about storage: they never make a fuss, so their weight goes unnoticed until a drive runs short. A folder of received attachments from a working project can reach several gigabytes, and a long-running group conversation can carry years of photographs and video. Both can be reduced, and in both cases the conversation itself can be left untouched.
Where Mail keeps its weight
When an attachment arrives, Mail stores a copy so the message shows its full content even when you are offline. Those copies stay until the message or the attachment is removed. Over years of work, the stored attachments become the largest part of the Mail group. Account settings that keep everything on the drive rather than in the cloud make the group larger still.
Find the largest messages
Mail can sort by size, which is the fastest route to the heavy items. Open Mail, choose a mailbox or the whole archive, then sort the message list by size. The messages at the top hold the largest attachments: slide decks, image sets, exported documents. Work down the list and decide, one by one, whether the attachment is still needed. Many are duplicates of files you already keep elsewhere.
Save attachments, then let the message go
The safe pattern is always the same: save first, remove second. Select the attachment, save copies to a folder on an external drive or to the Desktop, confirm they open, and only then remove the message or its attachment. Messages themselves are small; it is the attachments that weigh, so saving an attachment and removing the message costs you nothing but the copy you have already made.
Where Messages keeps its weight
Conversations store the media shared inside them — photos, video and audio clips — and these stay on the drive. A busy group chat can hold thousands of images. Messages groups media by conversation and by type, so you can review it without reading a single message. Open a conversation, choose to show its attachments, and you will see the media laid out for review.
- Open the conversationChoose a thread with a lot of shared media, such as a family group.
- Show the attachmentsUse the conversation's information panel to display the media it holds.
- Save what mattersSave the images and clips you want to keep to an external drive or to Photos.
- Remove the restWhere the system allows it, remove media you have decided against, leaving the conversation itself in place.
- Repeat for the heaviest threadsWork through only the conversations that carry real media weight.
- Recheck StorageReturn to Storage and confirm the Mail and Messages groups responded.
Trim without regret
Two habits turn this from a chore into a low-risk routine. First, save before removing, every time, and open a saved file to confirm it is sound. Second, change one thing at a time and recheck, so you always know what caused a change in the storage figure. Between them they mean you never have to recover from a mistake, because you never make one you cannot undo.
Removing an attachment does not remove the message, and removing a piece of shared media does not remove the conversation. The text of both stays where it was; only the file you chose to set aside leaves the drive.
Archiving old threads
For very old conversations you neither read nor need, archiving is gentler than removing. A thread moved to an archive is out of the way without losing the record. It is a good middle step for anyone hesitant to remove anything outright: nothing is deleted, the inbox is lighter, and the choice remains open.