iPhone and iPod touch have the ability to purge cached emails via Settings > Mail > Show Recent Messages. Note that this only affects the local copies of messages on iPhone and iPod touch and does not affect messages on the server. For additional details, see below.

When storing POP or IMAP email messages on your iPhone or iPod touch (i.e. emails stored in Sent, Drafts, and Trash folders), the purge feature for your IMAP and POP email accounts will start purging email messages on the device (throwing out the oldest cached email messages) once the