Thunderbird is an email client program installed on your computer. Each computer should have 'User Accounts' accessed by password. Each user of the computer should have their own 'User Account'. Thunderbird profiles are stored within each 'User Account'. So access to viewing emails would require access the User Account or user would need to have specfic admin rights to access everything. Profiles can store any number of mail accounts. A mail account is an email address. Thunderbird program is not a server. Thunderbird allows the creation of mail accounts for existing email addresses, so it can connect to the various servers that store emails and emails can be downloaded and viewed in one place within Thunderbird. It means you do not need to access the webmail account via a browser in order to see emails. Email receiving/sending protocols pop imap and smtp. Connection Security and Authentication methods. Emails can be encrypted. * https://support.mozilla.org/en-US/kb/digitally-signing-and-encrypting-messages Privacy and security Settings: * https://support.mozilla.org/en-US/products/thunderbird/privacy-and-security-settings https://support.mozilla.org/en-US/kb/configuration-options-accounts If you allow it, thunderbird will collect data in the event of a 'crash'. This data does not include 'personal' data. It does include the OS and any extensions in use and what modules were involved in the crash.