Free up app storage

Free up Mail storage

iOS Mail downloads messages and attachments into the Mail app. IMAP and iCloud mail still live on the server. Local downloads are what fill iPhone Storage. Deleting a message from a mailbox is not the same as clearing a cache. Trash still uses space until you empty it.

See how much space Mail is using

1. Open the iPhone Settings app.
2. Tap General > iPhone Storage.
3. Tap Mail.

Large totals are almost always attachments, not subject lines.

Download Attachments

1. Open Settings > Mail (on newer iOS: Settings > Apps > Mail).
2. Tap Mail Accounts / Accounts, then an account.
3. Look for Download Attachments, Mail Days to Sync, or Advanced mailbox options.
4. Choose a smaller window, or avoid downloading every attachment automatically if that control is present.

Mail still keeps the message on the server. You download a large file when you open it. Attachments you already saved with Save to Files or Save Image stay in Files or Photos until you delete them there.

Find mail with attachments

1. Open Mail and go to the mailbox list.
2. Tap Edit and enable the Attachments mailbox if it is not shown.
3. Open Attachments and delete threads whose files you do not need on this phone (and in the account, if this is a synced mailbox).

You can also open a mailbox, turn on filtering, then Only Mail with Attachments.

Mailboxes: Trash, Junk, and All Inboxes

1. In Mail, tap back until you see Mailboxes.
2. Open Trash (or All Trash if you enabled it).
3. Select messages and delete them to empty Trash.

Emptying Trash permanently removes those messages from the account after the provider's retention (iCloud Mail keeps deleted mail for a limited time, then it is gone). Junk can be emptied the same way. That is mailbox data, not cache.

Load Remote Images

1. Open Settings > Mail.
2. Turn off Load Remote Images if you want fewer images fetched into Mail.

On My iPhone accounts

If a mailbox is On My iPhone only, those messages are not on a server. Back them up or move them to iCloud / IMAP before you delete Mail data or erase the phone.

Reinstall the app if storage is still high

If you already cleaned media and Mail still looks huge, a fresh install can clear leftover cache and temp files that are hard to reach by hand.

1. IMAP and iCloud mail stay on the server. Move or export any On My iPhone mailboxes first. Attachments already saved to Files or Photos stay there. Mail is a built-in app; offload is safer than treating it like a third-party reinstall.
2. Delete the app from your phone.
3. Restart your phone.
4. Install Mail again from the App Store or Google Play.
5. Sign in and restore from backup if the app offers it.

This often frees a lot of space. You may need to download some media again after restore.

What to do next

After Mail is lighter, check your photo library for duplicates and similar shots. That is what Dedupo is for.

More app guides: Free up app storage.