IMAP email accounts on iPhone, data usage, and symbolic link of username in the home directory

Dear all,

I am writing this post and opening this thread in an attempt to try to resolve an issue that occurred to me during the last about 10 days. I was using the latest iOS 4.something on an iPhone 4. Moreover, there was one email account using IMAP set up among the email accounts that I track through the phone. My contract is with AT&T and typically my data usage is about 660 MBs per billing cycle (one month) +/- 5% of that. However, about a week ago I started receiving alers from AT&T because I was about to exceed my data plan (2GBs per month). Fine. I went to AT&T and they couldn't tell me which app was causing the problem, as online - before the end of the billing cycle - the entries are "Internet/MEdia Net" (the direction appeared as "Sent"). I then go to an apple store. They are telling me that probably a third party app is causing the problem, so probably the best solution is to wipe out the entire phone and install the latest OS. Even though I do not want to install iOS 5, I agree, and we did that last Wednesday (5/9). Again fine. Alas, the problem remains. When I came back home I restored the latest state before installing iOS 5 so that I can recover my contacts. During this recovery process, my email accounts were set up again. I also installed a couple of apps that I tend to use daily. The charges kept on accumulating online, so I deleted the two third-party apps I had reinstalled and the only third-party app that I left installed was that of AT&T (myAT&T). Again, the charges kept on accumulating.

Hence, the problem now lies either on the hardware of the phone, or somewhere in the AT&T app, or somewhere in the default software of the phone that uses internet access. Last night I attempted to check the email account that I have which uses an IMAP server. Even though it appeared as if it was trying to download data and populate the entries on the table view of my individual emails in my inbox, nothing showed up. Hence, I thought that this account might actually cause the problem. Indeed, I deleted the account and kept the phone turned on during the entire night and today I saw no extra charges while I was sleeping last night. Earlier this afternoon, I sent an email to the administrators in our department asking if they made any changes on the mail server and explained to them the entire situation. The answer was quite enlightening.

First of all, a symbolic link was created on May 3rd in my home directory which is associated with the "problematic" email account. The symbolic link was

lrwxr-xr-x 1 myusername root 31 2012-05-03 15:24 myusername -> /afs/department/user/myusername

Apparently, this symbolic link (which I did not create) caused some sort of "infinite loop" and the phone kept on trying to retrieve my entire home directory over and over again. Now I have deleted this symbolic link. For completeness my email address is: myusername@department.

Second, I was also told to set the imap prefix to "mail" since that is the mail directory that I am using. I also changed that entry because it makes perfect sense. In the past I could actually see my entire home directory in the department under this email account, and now I can not - just the emails - which is preferable.

Finally, I was also told that the administrators have seen these links in the past, but they do not know where they come from. Hence, one possibility is that the iphone mail app creates them, since the app has permission to do anything at all once it connects to the imap server (and remember, in the past I was not using any imap prefix for that specific account).
Hence, closing, I want to ask the following. Is it expected for the mail app to create such symbolic links? And if so, what purpose do they serve? Have you encountered such an issue in the past? Perhaps the above suggest some form of bug in the mail app and the way it treats the symbolic links and perform indexing? Do you have any other suggestions on what to check for the excessive data usage? I really do not want to end up paying a big amount of money to AT&T because of that. I am just a graduate student and so far I have used 5 GBs in excess of the 2GBs of my plan.
Any comment or answer to the above questions will be deeply appreciated. Thank you in advance.