What do you like best?
The best thing about Thunderbird is the ability to set it to deploy with pre-configured settings for multiple operating systems. For example, Server Admins and some programming staff may be necessary to work on linux/unix operating systems. As such, it can be deployed on those machines with their needs in mind.
On the other hand, business administration employees whose tasks would be better suited for Windows machines can likewise be very similarly configured before being deployed on those machines.
Not to mention, the graphical design teams tend to prefer Mac/Unix machines, and can be configured and deployed very similarly on their machines as well.
It truly allows for a cross operating system deployment with minimum extra effort spent by the IT department.
What do you dislike?
I can't particularly think of anything that I dislike about Thunderbird. It is cutting edge as far as scalability, security, and has excellent native-support for all common operating systems. Furthermore, it creates a unified environment for company users, so that it is only necessary to train/troubleshoot employees on a single email system. This creates less of a burden on the IT Department, and it keeps users from having to learn a new system any time they may transfer to a different department.
Recommendations to others considering the product
For anyone that has reason to deploy multiple different operating systems within their company, and wish to maintain some uniformity in the email clients their employees utilize.
What business problems are you solving with the product? What benefits have you realized?
The major problem solved is having a uniform platform that all employees employ. This reduces confusion drastically when troubleshooting. It also allows user to take advantage of the Thunderbird scheduling features to keep employees on the same page on regards to meetings etc. Also, due to Thunderbird being available software that they can utilize on their personal devices, it allows employees to stay connected from their home environments if they are authorized to do so. If they are not, then it is configurable to deny access from outside the work environment. All in all, it helps with workflow, security, and uniform communication throughout the company.
I have uploaded a screenshot of my personal Thunderbird account due to confidentiality agreements.