As a security precaution, connections from scripts on your account to foreign SMTP servers are not allowed by default.
Sending email messages through our SMTP servers does not require enabling connections to foreign SMTP servers, so please enable this setting ONLY if you want to send messages from scripts on your account through third-party SMTP servers.
You can allow scripts on your account to connect to foreign SMTP servers by following these steps:
Access your hosting Control Panel.
Go to the Mail Manager section.
Select the Extra settings tab.
Click on the Enable button from the Foreign SMTP servers section.