You can setup an entire company, regardless of size, in less than two minutes:
First, ensure your email provider is accepting password authenticated IMAP access.
Second, provide the username/password of any email account (when prompted during the login process).
Third, provide the IMAP and SMTP settings when prompted to do so.
Now everyone in the company can use TocMail to access their emails. They simply sign in using their respective email addresses and passwords.