Version:           unspecified (using KDE 4.4.3) 
OS:                Linux

Whenever I change a contact or appointment which are stored in IMAP folders, Akonadi just updates the content of the Email, but not its date.

Synchronisation programs can make use of the date, as they only need to fetch the Email headers to determine if something has changed. This is especially useful for mobile devices where traffic is expensive and slow.

Without updating the date of the email containing the xml file, one needs to downlaod the full email and build a hash value over the content.

Reproducible: Always

Steps to Reproduce:
1. Create a Contact or Appointment in Kontact/Kaddressbook/Korganizer
2. Select a Kolab Account to store the data
3. An Email appears in the IMAP account, containing the XML file with the information and the mail has the date of when the contact/appointment was created
4. Edit the contact/appointment, then sync/fetch the mails again on the IMAP account


Actual Results:  
Data are changed as expected inside the XML but the date of the Email is still the old one, not the timestamp of changing the contact/appointment

Expected Results:  
The date of the email containing the xml file should have change to the date of changing the data.