If you have an iPhone, you possible already had a problem with syncing. One of the most popular one is iTunes could not sync mail accounts to the iPhone "..." because the iPhone cancelled the sync. You can desperately try it again and again, but no miracle happens.
First of all, start looking for the change that could create the problem. In my case, it was change in SMTP server setting for one of the accounts. I was able to nail it down pretty fast. So how can we fix it?
- Go ahead, and open iTunes, then open iSync, and in Preferences clear all sync history.
- Restart iTunes. In the Info tab you should see mail accounts sync checked on, but no accounts shown.
- Restart iPhone, make sure mail application is not in the middle of something, hold Home button for several seconds, until it goes back to home screen.
- Find the account that supposed to cause the problem on your iPhone and delete it.
- Click on sync in iTunes and make sure that it will replace mail account settings on iPhone.
If you're lucky enough, you're good to go. You may repeat sync process several times, if no error message shows up, but account doesn't get sync. It will, eventually.
Have fun!(read more on Everytalks)