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How to fix a 550 permanent failure for one or more recipients in your email marketing

Updated: Jul 25, 2023

You just sent out a stellar email to a select few people on your email list and you get a 550 error message back.

What does that mean and what can you do to solve it? This typically comes from a Simple Mail Transfer Protocol (SMTP) error.

You may have received the message because the recipient server blocked the message.

We’ll dive into why you’re getting this message, how to solve it and how to get back on the email marketing horse afterward.

550 permanent failure

Why are you getting this error message?

Don’t take the email error message personally, it’s one of the most common 550 alerts that hosting users receive when they send out an email. Uncovering the reason behind it, though, can help you avoid the issue in the future. Here are some common mistakes caused by a bounceback message:

  1. The recipient temporarily disabled the sender’s email.

  2. The receiving domain inbox is full and cannot receive any more messages.

  3. The hosting email server marked your email address as spam and blocked the message.

  4. The recipient’s email hosting server blocked your IP address.

  5. The recipient’s email address does not exist or can’t be found.

While a lot of these issues are on the recipient’s end, there are ways you can configure your email-sending best practices to ensure better outcomes.

What is a 550 error message permanent block?

Imagine you’re browsing a website and you click on a page with a 303 error code saying that the web address you’re on is trying to redirect you to another page. This is similar to the 550 messages.

It is saying that the email server has an authentication issue regarding the SMTP server. Authentication issues are typical.

Don’t worry, it’s a pretty common mistake that may have occurred, but it will take some effort to diagnose and fix the problem.

Error 550 Message Rejected

If you send more than 500 emails a day on Gmail or more than 2,000 emails on a Google Workplace account, you risk getting your email blacklisted.

In this case, you may receive a 550 Message Rejected alert that lets you know that your email domain has been added to the Real-time Blackhole List (RBL).

In this case, you’ll have to work toward getting whitelisted again and marked not as spam (more on that next!).

6 ways to resolve a 550 permanent failure error

It’s exciting when you have a long email list of interested readers that look forward to your content.

But it’s important to ensure that your emails are protected against spam. Here are 6 ways to resolve a 550 permanent failure for one or more recipients you can implement right away.

1. Check the email address

You might have just input the recipient’s email address incorrectly.

Confirm what address they added when they signed up and add in the correct information. Ensure the address exists as well.

2. Limit the number of emails sent a day or per hour

When launching an email campaign, it’s important to keep in mind that email service providers (ESPs) pay attention to the number of emails you send out each day.

ESPs put a hard limit on how many emails a domain can send out in a certain time frame and could mark your domain as a spam account.

This can affect your domain reputation and put you on the blacklist.

3. Send a blacklist removal request

Sometimes you may be past the point of no return and you’ve found yourself on the blacklist already.

In this case, you’ll need to send a request to be taken off the list. Most domain blacklisting services offer a delisting form you must fill out.

You’ll need to provide your name, domain and a valid reason for the delisting. Depending on the dedicated server, you’ll likely get off of the blacklist after 3 to 5 days.

4. Change your 25 mail port

Many ESPs have begun blocking SMTP traffic on port 25. If you are able to receive messages but you cannot send emails out, you may need to change your SMTP service port to 26 or 587.

Port 25 has been used for decades to send mass emails and ESPs are starting to block home internet connections from sending out these types of messages.

You may benefit from switching to a new port to avoid further frustration.

5. Keep an eye on spam-triggering phrasing

There is an ongoing list of words and phrases that may trigger ESPs to mark your email domain as spam.

Things like using all capital letters, lots of exclamation, question marks or phrases like “win lots of money” are just a few examples.

We’ve all checked our spam folder for a message we’ve been waiting for and seen these types of headlines attempting to convince you that you’ve won a raffle you never entered.

6. Run a malware check

Sometimes malware was installed in your computer without you noticing it. Run a malware check and app removal for a system comb-through so you know your computer is clean and running well.

If you’re not sure why your domain was blacklisted, this could be the reason why. Viruses can get into your email account and send mass spam messages using your domain.

While your business gains more traction, cybersecurity measures are a must. You need to ensure that all of your operating systems are protected from cyber-attacks so your customers trust you to protect their information and your data is never compromised.

Set up Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication Reporting and Conformance (DMARC) under your domain name to properly defend yourself against attacks.

Warm up your email marketing too

But first, you’ve got to warm up your email!

It’s great having a long email list, but you may need to gradually send out emails and gain a better domain reputation first.

Your domain reputation — also known as your sender reputation or email reputation — is like your credit score: It tells ESPs that your emails are safe from malware or phony money schemes and that the content is valuable to the reader.

If your reputation is lacking, then the ESP will likely decide that the email domain is essentially dead and block all outgoing or incoming emails. Any email you do send will be sent straight to the receiving domain’s spam folder.

Your IP score is similar, but your domain reputation will take precedence over your IP address when an ESP is determining which folder to send your email to.

What impacts your reputation?

Keeping track of how your email is received is important for understanding your domain reputation and avoiding getting blacklisted. Your score is based on how recipients respond to your emails. Things like marking your email as spam or unsubscribing can negatively affect your reputation.

While this isn’t always avoidable, it is helpful to know what may drive someone to make such a decision, such as:

  1. Spam-y wording in your heading.

  2. Sending a lot of emails in a short period of time.

  3. Not getting the email addresses right, causing email bounces.

  4. Quality of the content and links within them.

  5. Audience engagement rates.

  6. Opening rate.

Each of these don’t carry that much weight individually, but if enough people are reacting negatively to your emails, this could put your domain in the danger zone.

How do you send an email to more than 500 recipients?

When you have a well-performing newsletter or an email campaign with a lot of people on the list that have shown interest, you may end up with more than 500 recipients.

These emails must go out so what can you do?

Depending on the type of ESP you’re using, there are features that help support business initiatives.

Adding their email addresses to the ’cc’ or ‘bc’ line won’t help. Instead, Microsoft, for example, has an email merge component that allows you to both send emails and personalize them as well.

Hit inboxes the first time with Warmup Inbox

Email marketing shouldn’t have to feel like rocket science.

We’ve taken the weight of getting your email just right off of your shoulders with our email solution.

Unfortunately, you can’t send hundreds or thousands of emails right out of the gate, you have to warm up your domain first.

Typically the process involves slowly releasing emails and building trust with recipients and ESPs. The process takes between 8 and 12 weeks to build a positive history.

But that’s where we step in.

We’ll help you develop your reputation with a system that really works and build helpful reports regarding ways to improve. With Warmup Inbox your email campaign can avoid annoying error messages so you can speak directly to your most valued customers.


Start landing in more inboxes. 
Use Warmup Inbox to improve your sender reputation and increase your deliverability.

No credit card needed!

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