Spam is a constant threat that comprises almost 80% of all email sent on the planet. In an effort to do our part and protect both our servers and customers, we have recently implemented outbound spam filtering. This page is to help those customers that are getting the error below in their emails:

550 This message was classified as SPAM and may not be delivered

Common Fixes for the Error:

Solution #1 - Ensure SMTP Authentication is enabled in Outlook

The Microsoft Outlook email client seems to be causing email messages sent through it to score higher than normal, causing emails that otherwise would be allowed through to be classified as spam. This is most commonly caused by not having SMTP Authentication set in the Outlook. Check out our article on Invalid HELO Names for instructions on setting that correctly. You should then be able to send normal emails properly via Outlook.

Solution #2 - Check your email content

Our email servers are using spam evaluation process that is set to the most lenient levels. This means it is difficult for your emails to be tagged as spam and prevented from going out unless they have a lot of features of a spam message. However if you are still getting caught by the filter, you will want to evaluate both the subject line and body content of the message to ensure there are not any references to popular spamming terms.

Solution #3 - Contact our Live Support Team

If you have attempted solutions one and two above and are still getting caught by the outbound filter, you will want to contact out Live Support team. When contacting them, please be sure to send the entire bounced email, including the bounce back headers. Forward the information to This email address is being protected from spambots. You need JavaScript enabled to view it. and our support team will then take the email and find its records in the filtering logs to see why it was blocked.

What is outbound SPAM filtering?

We have customizable spam filtering tools already in place for each account that evaluates incoming emails. Outbound SPAM filtering is a process where any outgoing emails will be checked as to the likelihood of the message beign spam. This is not customizable on an account level and is handled by your hosting server. It checks for multiple characteristics and assigns points for any it finds. If the email reaches a certain level, it is classified as SPAM and not allowed to leave the server. If you are receiving a bounceback with the error "550 This message was classified as SPAM and may not be delivered", then the email you sent has not passed the outbound filter.

Email to any recipient can always be determined to be spam based on content. The number of recipients for outbound emails are limited to 50, so it is not typically used as criteria in determining that an email is spam. The recipient field is only used as criteria for allowing or dis-allowing emails when the recipient has been explicitly placed on a blacklist or whitelist. This can be done in Spam Assassin.

Why are you doing this on outbound emails?

Outbound screening helps to preserve the reputation of our server's IP addresses. If an email server's IP gets enough spam complaints against it, it will be reported and blacklisted by a blacklisting service. Any email server that subscribes to that service will then block any mails coming in from that IP address. It is also possible that any emails coming from any of our servers will eventually be automatically being delivered to spam folders, regardless of the IP address of the server. As most of our customers do legitimate business online, it would be unfair to allow our server IPs to be classified as spam because of a few abusers, hence the outbound spam evaluation.

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n/a Points
2014-04-11 11:19 pm

I am trying to forward a phishing email to and it gets rejected because it is obviously spam.

How is one supposed to do this as requested by American Express?

14,194 Points
2014-04-12 3:42 am
Hello Len,

Probably the best thing to do is to export the email into a text file and then save it - make sure to include all of the headers. Save the TXT file as an attachment and then send it. If you have access to make the email into a PDF, then that's another way to attach and send it. You can also save the file as a TXT file and then make it into a file that can be shared via service such as Dropbox.

Hope that helps!

Arnel C.

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