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

Common solutions to the error

Solution #1 – Enable SMTP Authentication in Outlook

If you are using the Microsoft Outlook email client, not having SMTP Authentication will cause several points to be added to the spam score. This can cause emails that otherwise would be allowed to be classified as spam. You can find instructions on enabling that setting that in our Invalid HELO name article.

Solution #2 – Evaluate email content

As our outgoing servers are using a spam evaluation software set at the most lenient levels, 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. If you are getting caught by the filter, evaluate both the title and body content of the message to ensure there are few, if any, references to popular spamming terms.

Why am I getting this error?

To help in the global battle of ever-increasing spam, we have implemented spam detection procedures on all emails prior to leaving our servers. Each email is evaluated and rated according to spam rules to determine how likely they are to be actual spam. Those that fail the test are returned to the original sender with the error message 550 This message was classified as SPAM and may not be delivered (please see the email below). If you are receiving a bounceback with this error, then the email you sent has not passed the outbound filter.

Why are you doing this on outbound emails?

Although email servers review all incoming email and evaluate it against their own filters, we have begun screening outbound emails to help preserve the reputation of our server’s IP addresses. Once a mail IP gets enough spam complaints against it, it will be reported to a company that maintains a blacklist. Any email server that subscribes to that particular service will then block any incoming email from that IP address. After too many times on a blacklist, any email sent from our servers has the chance of automatically being delivered to spam folders, regardless of the IP address of the server. Also, since many of our customers are on shared servers, we feel it is not fair for your emails to be blocked due to the spamming activities of other customers. Outbound spam evaluation is a proactive measure to prevent blacklisting and keep your email server up and running.