Are you using the Apple Mail application?
If so please go to the Apple logo at the upper left of your computer screen to About This Mac and give me this information: The exact system Version (listed right under Mac OS X) Processor Memory
Reboot into the Recovery HD by choosing the ‘Apple‘ menu > Restart, hold down the ‘Command’ + R’ keys on the keyboard during the start up process when you see the Apple Logo you can let go. When the machine boots eventually you will see the OS X Utilities screen., select the Disk Utility and then select Continue. Then in Disk Utility select Macintosh HD in the left column, if there are two or it is named something else choose the first indented item, and then select Verify Disk on the right. If that is OK in green type then select Repair Permissions. If it is not ok let me know.
the Apple Logo to Restart
Ok but also Verify the first indented item
So Verify Disk was OK in green type and then you Repaired Permissions?
What is RHS? Ok so Macintosh HD Verify Disk was OK in green type and then you Repaired Permissions?
Not on the right hand
When you run Verify Disk in the results??
It will say the disk is OK in green type
Not the Base System Macintosh HD
Anyway if that is ok restart and open Terminal in Applications / Utilities copy and paste this line then hit Return then try Mail: rm ~/Library/Containers/com.apple.mail/Container.plist
I made an offer to connect by remote
Not Teamviewer but similar
You have to Accept the offer.
No there is a button do you see it?