There lies the ironic reason I now use Thunderbird/Lightning, only the compatibility issue was outlook on outlook. I was using Outlook 2000 at home and at work. When I created events with Outlook 2000 at work, and sent the invitations to my home email, they would come in the form of a text email rather than an event and I had to manually re-create the event in my home outlook calendar using the information from the text.
I tried Thunderbird/Lightning just to check it out, and now when I send an Outlook event from work to my home email, Lightning recognizes it as an event and I can simply click "accept" and Lightning auto imports the event into my calendar. Why Lightning will work with outlook, but outlook won't work with outlook, I'm not sure. But that was the reason for my switch and now preference for Thunderbird/Lightning.
I tried Thunderbird/Lightning just to check it out, and now when I send an Outlook event from work to my home email, Lightning recognizes it as an event and I can simply click "accept" and Lightning auto imports the event into my calendar. Why Lightning will work with outlook, but outlook won't work with outlook, I'm not sure. But that was the reason for my switch and now preference for Thunderbird/Lightning.