The way MailStore works is something like this. You install (or unzip)
the software to a folder and then select the email accounts that you
want to archive. They can be your Gmail accounts, Microsoft Exchange,
your old Outlook PST files, Thunderbird and any other web email service
that supports either IMAP or POP3.
The tool will pull your email messages from all these places into a
central location. If you have a large mailbox, you may specify criteria
to skip emails that are older than ‘n’ days. It skips the Spam and Junk
folders by default but you may also manually specify any folders /labels
that you wish to include (or exclude) from the backup.
That’s it. There’s a convenient search box allowing you to search all
your email accounts from one place. You can copy the MailStore folder to
your USB drive, or even your Dropbox folder, and access all the emails
from anywhere, anytime. Since this is more of an email backup utility
and not a full-blown email client, it cannot be used for replying or
sending new emails.