Could not send Mail through Office 365 Send mail plugin

I have tried to use Office 365 Send mail plugin But it will not send the mail I will get the message that “Your message wasn’t delivered because the recipient’s email provider rejected it.” But when I send the mail manually it will send properly.

@KalyaniW Kindly help resolve the query.

Hi! Akash,

Please can you ask the client to check if it is related to firewall settings?