IPhone 5 (16GB) iOS 7.0.4 Mail App size is 1GB and continuously increasing. How to reduce the size of the Mail App?

Question

Hi,
I am using an iPhone 5 (16GB) iOS 7.0.4.
Currently the size of the mail app is 1GB and is continously increasing, even though the advanced settings in the mail account have been set as following:
MOVE DISCARDED MESSAGES INTO:
Deleted Mailbox
DELETED MESSAGES:
Remove: After one day
INCOMING SETTINGS:
Delete from Server: When removed from Inbox
The problem that I am facing is that only a few emails reside on my iPhone as I keep deleting emails, which are also deleted from the server automatically because of the settings as above, which is perfectly fine. The emails are deleted from the Mail app and only a very few of them are visible which I have not deleted as yet, and all is fine till here. The problem is that the size of the Mail app is more than 1GB and is continously increasing, when i check the size of the Mail app in the Settings > General > Usage section.
When I search for an email that has previously been deleted from the search feature by swiping down in the main page, it still comes up in the search, and upon clicking the searched email, it takes me into the Mail app, however, the mail is not there. I have tried searching for emails which were deleted weeks ago, and they still come up in the search feature, however, they DO NOT open in the Mail app when i click them within the search feature in the main page.
Up until a couple of months ago, the size of the Mail app was about 5.2GB and at this point I had no space on my 16GB iPhone 5, therefore I resetted my phone two months ago, and after a complete reset of the iPhone 5, the size of the Mail app went back to 0.3KB (like it was brand new out-of the box); however, within a matter of two months the size of the Mail app has now exceeded 1GB and is continously increasing, as I receive alot of emails which is why I delete them on daily basis and even delete them from the Trash folder (mailbox).
I have read alot of blogs and even checked with other friends using similar settings on the same model, however, I just cant seem to figure this out. I would really appreciate if someone can help me with this issue as I dont want to have to reset it again after another 2-3 months.
There are practically only 14-15 emails on my Mail app with not alot of KBs for these emails, and the trash folder is also empty, but the size of the Mail app is still not reducing. Please help!!
Regards,
Shoaib Malik

Answer 1

Have you tried restarting or resetting your iPhone?
Restart: Press On/Off button until the Slide to Power Off slider appears, select Slide to Power Off and, after It shuts down, press the On/Off button until the Apple logo appears.
Reset: Press the Home and On/Off buttons at the same time and hold them until the Apple logo appears (about 10 seconds).
Also consider deleting and reinstalling the Mail Account in question.