We previously reported on an issue where the "Other" storage on an iPhone inexplicably swells to inordinate sizes. Our old report indicated that the only effective fix for suddenly missing storage on the iPhone that occurs after a sync is to restore the device.
It now appears that, in at least some cases, a glut of email in the iPhone email client's Trash folder can represent a portion of the swollen "Other." Navigate to the trash box on your iPhone-stored accounts, and delete excess messages. Unfortunately, there's no method for deleting multiple emails simultaneously, so this can be a tedious process. For IMAP accounts, it's best to delete the messages via other means (your desktop/laptop, for instance), then delete and re-establish the accounts on your iPhone.
iPhone Atlas reader Anita Murray writes:
"Maybe this is just a fluke, but I found that by deleting all the emails in my trash (on iPhone), I got all my space back again.Â Twice now I have had so much 'other' that I couldn't sync my movies, until I deleted my deleted emails."
If "Other" is still taking up too much space, restore as previously prescribed. Connect your iPhone to your computer, then in iTunes, select your iPhone and click the Restore button under the Summary tab. Restoring the phone will erase contacts, calendars, photos and other data stored only on the phone, but will restore automatically backed-up information including text messages, notes, call history, contact favorites, sound settings, widget settings, etc.