When sending mail via your hosting account or server, the mail server needs to know that you are permitted to use our servers to send your e-mail in order to prevent any form of abuse of your account. Without this, spammers can send vast amounts of unsolicited mail via your account or our servers which can lead to blacklisting and so affect your ability to then send mail yourself.
Mail is sent via our servers using the standard SMTP protocol, however you must specifically enable SMTP Authentication within your mail client (ie Outlook, etc).
SMTP Authentication, often abbreviated SMTP AUTH, is an extension of the SMTP Protocol whereby an SMTP client may log in using an authentication mechanism chosen among those supported by the SMTP server. This is where your mail client passes your e-mail username & password to the mail server for every message that is sent, in the same say as it does when logging in to receive mail. This ensures that every time a message is sent from your IP address, your mail client re-confirms that it is authorised to do so.
Please note that the older POP Relay method for authenticating yourself has now been withdrawn from our servers as this has the potential for abuse. cPanel is also shortly removing this functionality altogether.
We have some downloads available within our client area (https://www.penguin-uk.com/clients/downloads.php?action=displaycat&catid=5) with instructions for how to enable SMTP Authentication for some popular mail clients. For assistance with any others, please open a support ticket and we will be happy to assist you where possible.