Note:If you want to password protect only one mailbox rather than all of your emails in mac 
mail,  please read this article:How to password protect only one mailbox in Mac Mail.

If you ask someone is there a way to password protect mailboxes on mac used  by mail
client:Apple Mail or Mozilla Thunderbird,they will tell you to make a separate user account for
each(or all) of your friends to take care of this issue-when your friends use your mac, they
cannot access your personal files and see your mails.
 

The Problem:

1.Additional user accounts wouldn’t be satisfactory, If you work in a team production
environment, where if say, you were out to lunch and someone needed to urgently access a
file you are working on and make a minor change.In this case the second user account would
need to also have access to all the applications and files (include the first user personal
mailboxes) that the first user has access to. And if you happen to lose your Mac, or if it’s stolen,
the whole contents of your hard drive will be copied without needing to login to your mac.

2.Another big problem is is that merely password-protecting the Mac Mail app or Mozilla
Thunderbird would not prevent access to your mailboxes. Your email is stored in files under
your home folder and is therefore accessible (using other programs) to anyone who has access
to your user account.  So password-protecting Mac mail app would be analogous to locking the
front door but leaving the back and side doors open.
 

The correct solution:

The correct solution is to password protect Mac Mail or ThunderBird’s profiles and mailboxes,
MacFort is an easy way to password protect Mac Mail folders, MacFort will move the mailboxes
to an encrypted vault, before you open Mac Mail or ThunderBird, you must supply the correct
password to unlock the encrypted vault first, if password enter wrong, Mac Mail will be denied
access to its profiles and mailboxes.

The Advantage:

1.MacFort use the features built in to mac os x to create the encrypted vaults, and works great
with Spotlight search and Time Machine, which will make your email files more secure and reliable,
so don’t worry about the possibility of data loss.

2.MacFort use AES to provides strong encryption for your email files, it is impossible to see
your email files without knowing the correct password.

3.You can even put the encrypted vaults in an external drive or a network drive, if you lost
your mac, your email files are still in a secure place.

 

First click “Scan” in the main toolbar,choose mail on the list,then click “OK”.

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

Now it is all done!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

      Next time if when you start Mac Mail,you must enter the correct password to allow
      Mac Mail to access the mailboxes first, see screenshot below:

        

        

 

 

 

 

 

 

 

 

 

     Click the button to download MacFort now!