Was "outbound to Internet" blocked as well?
- If the answer is no, double-check that you entered the correct SMTP server address.
- If the answer is yes, then you have to contact your host for an outbound mail solution. They may give you a different SMTP server to use, one that they own, with an email address that they own as well.
Unless you use a Gmail account, then you can ignore all that and go ahead and use the Postman Gmail API Extension as the plugin suggested.