Currently the only supported pop3/smtp servers for servers-side syncrhonization in CRM Online are gmail and Yahoo. The restriction is hard-coded, i.e. UI will not accept any server addresses besides those for the 2 services above.

System should allow specifying any compliant pop3/smtp server, e.g. smtp.sendgrid.net for outbound emails. In addition, ability to use arbitrary pop3/smtp servers would provide stop-gap for CRM Online Exchange On-premises integration.