Why is my email blocked?

Have you ever had an email blocked? This can be for many reasons, sometimes they happen unfairly. Email networks are constantly advancing, becoming more complex in the process. This is visible at mailbox providers such as Gmail, who are constantly innovating to provide a safer environment for email users. Want to set up your email in Gmail?

Similar to most business dealings, sender reputation is a key factor. For instance, if you have a newly registered domain, you will have a lower sender reputation score. Because of this, if you start sending 000’s of marketing emails from this newer domain, it’s likely you will experience email blocking. Or the emails arriving into a spam folder.

Sender reputation is in part determined by our mail servers IP addresses. However, not everything related to the mail server impacts email deliverability. For instance, check if your domain is on a reputation block list.

Email blocked for SPAM

All mail sent from the shared hosting services goes via a spam-filtering outbound mail gateway. This gateway exists to protect the IP reputation of our servers. And, therefore, the deliverability of all emails sent from our cPanel and Plesk shared web hosting servers. Alongside our spam filters, we also monitor spam complaints. If you send spammy-looking content from your addresses, you risk suspension.

This mail gateway examines every email sent from the shared server, considers its contents, and applies a numeric ‘spam score’.  When an email’s ‘spam score’ exceeds a certain threshold, the spam filter blocks the message.

This will usually send a bounce message. Bounce messages are easy to identify, check the subject of an email. For example, if the subject appears similar to below, this would indicate the email was blocked.

Mail delivery failed: returning message to the sender

It can be hard to make sense of the email headers included in these emails.
Essentially, some characteristics of the email caused our mail gateway to suspect that it was spam.

Throughout this article, we detail some common block reasons and potential fixes:

A common tactic of spammers is to send email phishing links. These links imitate real sites leading to fake sites and, sometimes, high-quality copies. Stay informed on Phishing and how it can impact your website.

Their purpose is to trick the person who clicks a link into believing they are on the authentic site. Afterwards, you might be asked to enter personal details, or the link can prompt a malware download.

It’s possible that a hyperlink within your email is triggering the mail filter, first attempt to re-send an email without any links. Do you receive a bounce-back? If not, it was most likely a hyperlink block.

Unsure? Get in touch with our support team.

Email Marketing

Do you engage in email marketing? If you run an email marketing campaign and don’t honour unsubscribe requests, it’s likely your messages will receive a spam complaint. This will damage your domain reputation, and it could be placed on a block list, check if your domain is on the list.

If you escape a block, it’s still likely the email will not arrive. Ends up in a spam folder and not the intended recipient’s email address inbox.

Invalid or missing SPF records

SPF records are a special type of DNS record that identifies the mail servers which are authorised to send mail on behalf of a domain. 

Large mail service providers such as Gmail and Hotmail increasingly take note of these. For example, when you receive an email, check it was sent from an authorised server, visible through the email headers.

Normally, when you create either a cPanel or a Plesk account, it is assigned an automatically generated SPF record. Therefore, if you’re using the correct DNS settings, you should already have a valid SPF record. However, if you’re using an external DNS provider, please check in with our support team who can verify your SPF is set up correctly. Want to change your nameservers?

Phrases & Capital letters

It could be that the content of your message, or the subject, happens to be using keywords that are commonly seen in spam emails.  Some examples of these are:

  • Free Offer
  • WORDS OR PHRASES ALL IN CAPITALS (particularly in the subject)
  • Lots of exclamation marks!!!
  • Sale
  • Generic salutations, such as ‘Dear Customer’
  • Banking terms such as Statement, Invoice
  • Phrases encouraging users to sign in, for example, ‘Sign in’, ‘Log in’, ‘authenticate’

Obviously, some of the above are perfectly legitimate, but together they may contribute to the ‘SPAM score’ of an email, which increases the chances of your mail being misidentified.

Attachments and images

Some spammers attempt to hide contents from spam filters by using images instead of text, and some phishing emails include attachments which they are aiming to trick recipients into the opening. 

As such, emails with low ‘text to image ratios’, i.e. just a small amount of text alongside one or more images or attachments, can sometimes attract a ‘spam score’.

No Subject / special characters / strange spacing

Emails without a subject at all are unusual and as such likely to be viewed with suspicion.  Similarly, another trick used by spammers is to try to hide the content of messages by using unusual character sets or S P A C I N G in text, to try to hide the content of the message from spam filters. As such try to stick to standard characters and formatting where possible.  

None of the above applies to my mail!

These are just a small sample of some of the more common reasons why mail has been identified as spam and blocked. 

If you would like some further insight on why a particular email was blocked, please contact our support team by raising a ticket through your client area of the website, and providing the from address, to address, and rough time at which the email was sent (note the logs of the mail filter are only retained for a couple of days, so it will need to be ‘recent’) and we will investigate for you.