Missing recipient address validation

[Mr-Raian]

Steps to reproduce

1. Create a contact with a domain as email address. E.g. Contact Joe has as email address joe.com
2. Go to Mail app and send new email
3. In recipients set the contact Joe as receiver
4. Send email
5. Now the email is stuck in Outbox, and it never alerts you about the problem

Expected behavior

Mail app should check if the email has the proper format and alert the user otherwise.

Actual behavior

The email is never sent and the user isn't prompt with any useful alert

Mail app version

1.13.8

Mailserver or service

No response

Operating system

No response

PHP engine version

No response

Web server

No response

Database

No response

Additional info

No response