DMARC Blocking.

Recently  my emails to my wife's account, [Edited: "Personal Information"],  I have been getting this message especially when an invite is sent through my mobile phone Samsung Calendar with invites for appointments. 

The weird part is she is getting plain emails I send but I'm getting this message but she is no longer receiving the Calendar Invites????,

Message blocked Your message to [Edited: "Personal Information"] has been blocked. See technical details below for more information. LEARN MORE This link will take you to a third-party site

550 5.2.0 NBD0uYgajzq6uNBD1uREvv Message rejected due to DMARC. Please see https://postmaster.comcast.net/smtp-error-codes.php#DM000001