Hi. I understand that your emails are disappearing once you read them. I will be happy to help you with this issue. When you read the emails, do you add it to your stored messages or another folder? To check, go into your email and click the menu option and see if the messages are auto stored to another folder.
If they are not, you may have them on auto delete. Basically go into your email and go to the menu options and go to your settings. Make sure the auto delete option is not checked.
Please let me know if this works
you need to access your email account from the pc that you use and go into your email program (outlook or whatever you use) and go into options and check "leave copy on server." you also may need to check this option if it exists in your settings on the phone.