Posted by Matthew Jeffels, Last modified by Paul Nesbitt on 22 September 2016 09:47 AM
What is SMTP Restrictions?
SMTP Restrictions prevents users from being able to send emails without going through a mail server which is a common practice among those who wish to distribute spam mail.
Without this setting being enabled mail can exit the server directly from any script within their website.
Enabling SMTP Restrictions causes access to send mail restricted to yourself (root), Mailman and MTA.
What this means is users wanting to send mail from a script on their website will have to send it through your servers SMTP daemon as an authenticated mail account.
Any scripts that attempt to bypass this will not be able to send email.
You can find additional control for this within Tweak Settings under the Mail section.