The problem might be due to the correct date and time were not set on the BlackBerry device before email service was activated.
Please correct the date and time on the BlackBerry device.
1.On the Home screen of the BlackBerry device, scroll to Options.
2.Click the trackwheel to open the Date/Time menu.
3. Set the Time Zone, Time, Time Format, Date and Date/Time Source to the correct values for your area.
4. Click the trackwheel and choose Save Changes.
These steps will not correct the time stamps of email messages that already have been received on the BlackBerry device. The only way to change the time stamp on an email message is to send it again and delete the earlier one.