http://kb.mozillazine.org/Limits_-_Thunderbird#Accounts

As far as I'm aware there is no limit, except for the obvious - you need to have the Disc Space. '''You can have several Profiles.''' when you initially download and run Thunderbird it will create the first default Profile. If you ever need to create more then use the Profile Manager: * http://kb.mozillazine.org/Profile_Manager '''Each Profile can have several mail accounts.''' To add another mail account File > New > Existing Mail account or 3bar menu icon > New Message > Existing Mail account You can have any number of Pop and /or IMAP mail accounts. Pop mail accounts can exist with their own set of folders or be set up as a Global account. Please read info on Global Inbox accounts: * http://kb.mozillazine.org/Global_Inbox '''Mail accounts can have more than one identity.''' To understand what is meant by identites, please read this info. * http://kb.mozillazine.org/Mozilla_Suite_:_FAQs_:_Mail_Aliases Info on Limits - * http://kb.mozillazine.org/Limits_%28Thunderbird%29