I'm not sure you want to have multiple users sharing the same profile. But it might work to have each user with their own profile, in which the 7 accounts are set up as IMAP accounts, so the mail is synchronized across all 13 users. Even then, you would have to set up a system that coordinates the actions of the users on the accounts to avoid conflicts. To set up all the accounts on all the users, consider the Autoconfiguration tools.

Those were the requirements given to me - dictated by HIPAA...each user must have their own Win login and Win requires admin for each user to access the 7 email accounts. I'm looking for a way to cut down on my admin of this matrix. And Webmail would require just as much admin - even if we left the accounts active (like gmail does) the users would still get logged out and would need login ID and Passwords to access email...and we don't allow the users to know the passwords...too much employee turnover here.

Using the same profile on the same machine for 7 users... not a problem as only one will be accessing it at a time.

Concurrent access to the profile from multiple devices is asking for trouble. Thunderbird is not even tested in such a multi access mode. But file contention is almost certain to be a problem.

Having a profile with a user name and password will in itself be an issue as Thunderbird makes the password visible to the user. You would be needing to use network authentication against the email server such a kerberos or a TLS certificate. Both would require the mail server to support that type of authentication.

What I do know about HIPPA, and it is little, is that email communications containing patient information to others other than the patient must be encrypted at all points in the delivery chain, basically s/mime or a third party encrypted web portal are your choices. But there are exceptions and you have to enforce them.

If you think you have issues with user turn over and passwords, wait until you try and enforce S/mime encryption of emails. Especially as it will only work with others that have encryption certificates, so basically patients can not be emailed because the USA unlike some other countries (Italy for instance) has not actually grappled with individual encryption of email. So under the exceptions you can send patient an email with patient data unencrypted, but not other providers.

Including a practitioner covered by HIPPA is a massively expensive thing in terms of support and idiot education. Some of your most difficult customers will be the doctors themselves. They want to delegate everything and also trust no one. But long term health employees that consider it "troublesome" and "a waste of time" will make implementation and control a pure nightmare. They will turn off required encryption, use web services and just about anything to not use the hated encryption.

Best of luck.