when I am sending calender invite from my outlook 2016
I am getting undeliverable notification groups:
The format of the e-mail address isn't correct. A correct address looks like this: firstname.lastname@example.org. Please check the recipient's e-mail address and try to resend the message.
like this I am getting 8 or 9 undeliverable notification for different email messages.
but when I send next time it goes through with just the email address
any reason why =SMTP: is coming beforeemail address