While working on Exchange 2013 you might face this issue when testing Mail Flow. The mails you send get stuck in the Drafts folder.
Sent mail goes directly into "drafts" of the user account and does not do anything else.
Resolution: This is mainly a DNS issue. Check your DNS settings and correct them accordingly. In case the issue occurs for Outside Domain mails, check with the external DNS IP .
On EAC, going into "servers", and on the properties of theserver, specify the external and internal dns server addresses.
1. Set the specific DNS settings in EAC to the IP of the DC (integrated DNS)
2. set MX record for the domain to the FQDN of the test exchange server.