I love that it can be used to convert emails from one format into another, which is great if you are looking for an easy way of converting your old email formats - even Outlook ones! It's also not too difficult or expensive so worth investing in as there really isn't anything about this program itself we dislike except maybe how long some messages take before conversion (which could easily have been fixed by just adjusting settings).
We use mail converter very frequently at work when moving data between clients/customers etc but don’t often need any additional software after purchasing since everything works perfectly well with MS Office 365 without having multiple copies installed around our network!