When you open a Mailock message in Outlook the add-in decrypts it for you to read, like the example shown below, but it doesn’t save an unencrypted copy with IMAP/POP3. In other words, it remains encrypted in your inbox or sent folder.
If you’d like to save a unencrypted copy you can either save to a folder or file.
Selecting 'Save to folder' (1) brings up an email folder selection screen:
You can select the applicable email folder and then select 'OK' to save your encrypted copy to.
Selecting 'Save to file' (2 as per email image above) brings up an email folder selection screen, as seen below, where you can select a location on your computer and then select 'Save' to save your encrypted copy to: