Mail - External HD - Folder Unavailable - How to Fix?

Good afternoon,

My Mac Mail directory is on an external hard drive. Everything was fine until I rebooted this morning and now I am getting the following error:

Mail can't continue because the folder where it stores informaiton is unavailable. Please make sure the ~/Library/Mail folder exists.

I checked the following solution, but it appears to be for a network drive issue:

Ok I got it, after profiling what does Mail.app do (thanks to Instruments) I eventually found the problem.

Mail access a folder which seems to be outdated or corrupted.

Here is to solve the problem i.e. to avoid this:

1. Go to the folder ~/Library/Containers/ using the menu "Go > Go To Folder" and enter "~/Library/Containers"

2. Delete, remove or rename the corrupted folder "com.apple.mail"

3. Open Mail.app, it should work

enjoy

The External Hard Drive is up, working and the folder is available. Any help or assistance you would be able to provide would be appreciated. When I use the steps above, it is looking at my standard internal HD with the Mac, and not the external HD where Mail is stored.

Thanks for you assistance.

Jen