Messaging and transport protocols
Microsoft Dynamics CRM E-mail Router supports a variety of e-mail messaging and transport options.
POP3-compliant e-mail systems are supported for incoming e-mail message routing.
When you use the Forward Mailbox option on the User form, the POP3 e-mail server must provide support where an e-mail message can be sent as an attachment to another e-mail message.
If you configure the Microsoft Dynamics CRM E-mail Router to connect to a POP3-compliant e-mail server, the server must support RFC 1939.
Both SMTP and Exchange Online with Exchange Web Services (EWS) are messaging transport protocols that are supported for outgoing e-mail message routing.
If you configure the Microsoft Dynamics CRM E-mail Router to use an SMTP-compliant transport service, the server must support RFC 2821 and RFC 2822.