I have 2016 version but rarely use macros. Created one to test this - it does not ask me for an object name or type to send. Perhaps you have something in the 'name' property field, or have selected an object type without specifying a name? Outlook was already open, but I don't think that would make any difference to the behaviour you're describing.
It's a very limited method for sending emails, and I had to deal with the Outlook security 5 second warning and delay, which is another reason why not many of us here would use a macro for sending email.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.