Outlook Meeting Request Message was Empty
I am working with my clients and I used to send them emails for our business transactions.
Lately, when I sent them a meeting request, most of them are complaining that my message was empty.
I am using Outlook 2010 and I know that some of them are not using Outlook but Thunderbird instead.
What can I do to fix this aside from sending regular mails instead of actual request for a meeting?