Zoho mail not sending to some mail clients

Zoho mail not sending to some mail clients

I am able to receive mails from everywhere able to send mails to gmail and other clients as well. But on some of the clients mail not receiving some time before they are receiving everywhere but now we are trying from last two days with no luck.

My super administrator email is admin@bmwindia.co.in and sending to microsoft outlook client and mails are receiving there.

Kindly look into this matter on urgent basis.