Issue while inviting users

Issue while inviting users

Hi,

I am trying to invite portal users ; but it gives me error .

For some of emails it is working ; but for some of emails it is not.


emails which are working  - 

emails which are not working - 


please find erre message - email.PNG as attached.


and let me know if you need other details.


Please check and let us know what is the issue.


Thanks and Regards,
Sidhant A.