Require Full Email Address

Information Details

Normally, the reason you have reached this page is because a mail server has sent you a message when it rejected an email from you, or one of your users.

  • If you are an email or network operator, you can continue reading this section
  • If you are a user sending email and it got blocked, you should read this section instead

Information for Email and Network Operators

Although email servers can by RFC accept connections that are simply addressed to ‘john’, most email servers support many different domains, and in practice any one who doesn’t include a domain does not supply enough information to safely route email. This is a simple rule which just insists that the ‘@’ symbol be part of the address.

In order to ensure that messages are not stopped by this check, make sure the FULL email address of the recipient is used.

The RCPT TO: string received should in the style of:



The following bad examples will get rejected:


Spammers will often try to send email to just ‘john’ hoping that user exists on a system. It is a lot harder for them if they are required to use valid domains. If you are the one sending the message, and you were blocked with this message, it is most likely that you do not have your email client set up correctly, and you should read the next section.

Information for users. Why was my email blocked?

If your email was blocked, and the link sent you here it is probably because your email client is not set up correctly, or your outgoing mail server is setup incorrectly. This is NOT the From: information that you type in your email, (ie in the section where your email client shows To:, From: and Subject:) but this is normally what you use as login information or setup information for your email account.

The main problem will usually be in your email/account settings, (eg. in Outlook or Thunderbird)

Carefully check the To: address in your sent folder and you will usually see the simple mistake. Make sure you use the FULL email address. Sometimes this rule can get triggered if you include strange characters in your to address, that your outgoing mail server did not know how to parse correctly.

Normally, this rule will only block spammers who try to send blanket email blasts to common names hoping that the recipient exists on the destination server. Please check the email address that you tried to send to, and once you fix that you can try again.