Knowledgebase

Is Gmail refusing to talk to you?

If your email is being blocked by Gmail, then someone or some application has spammed them.

You may say, “Hey, I am not a spammer,” but Gmail does not care too much about what you say about the email you send them.  They based their blacklisting decisions on a number of parameters.  If you trigger one of these, then your email may get blocked.

Fortunately, I am getting ready to tell you my tips on how to remove your IP from the Gmail Blacklist.

Why Was I Blacklisted?

Gmail does not publicly disclose their email filtering policies, but a key feature used by almost all email filtering systems is sender reputation. Sender reputation attempts to place a score on how likely email originating from your server is going to be spam. Scoring methods are complex. While I don’t know Gmail’s specific methods, most systems take into account:

All of these factors go into determining your sender score. I recommend you always check your sender score before doing any blacklist removal requests. Many ISPs rely on sender score from ReturnPath, so I always check it there. Even if Google does not use this directly, a low score there likely signals broader email delivery issues.

Top 4 Ways to Get Blacklisted

As part of our server support packages, we help a number of businesses get remove their IP from Gmail’s blacklist.

In our investigations, the most common reasons why Gmail blacklists your server are:

• Compromised user account used to send spam.
• Web application exploit used to send spam.
• Bulk emailing from mailing lists, newsletters, forums & blogs (even if they are opt-in).
• Bulk forwarding of email to Gmail.

The four items account for about 95% of all spam cases we investigate

The first two are security issues. Poor passwords and outdated web applications are hacker favorites. In either case, a compromise can mean 10,000’s of emails get sent to Gmail in a matter of hours. Such a breach will certainly land your server’s IP on their blacklist.

Another source of blacklisting is notices from forums, blogs or newsletters. Even if the person subscribed to the email and you provide opt-out information, Gmail may still flag your email as spam.

Lastly, forwarding large amounts of email to Gmail can trigger a blacklisting. We see this when people forward email blindly to Gmail. They then mark the email as spam. The result is that your server’s sending reputation is penalized since it was the one that last sent the email. This is a commonly overlooked reason for blacklist inclusion.

Double Check DNS

If your DNS is not correct, you may have email delivery issues — even if you found no malicious activity.

DNS goes beyond just having a MX record. You need to check and verify the following:

• Sending server’s hostname resolves
• Reverse DNS (PTR) for your email server
• SPF, if present, is correct
• DKIM, if used, is correct
• Domains used in email headers resolve

You can use tools like IntoDNS and DNSStuff to verify your DNS Is correct.

Are You a Server Admin?

These tips are for system and email administrators who have access to their email servers logs. If you are a end user or use Google Apps, then you will need to contact Google directly for assistance.

If you are a server admin, don’t just jump to where I have the URL for the Gmail blacklist removal form.

If you don’t fix the issue, you will just get re-listed – perhaps permanently.

Blacklist vs Spam Folder

So your email is going into Gmail’s Spam folder?

Great news. You are not blacklisted.

If you are blacklisted, your email will be rejected with a 421 or 550 SMTP error. You can spot this in your email server’s logs:

Example of a 550 Error:

Example of a 412 Error:

If you see either of these errors, then you are blacklisted and you can work on getting off the list.

Deciphering Gmail SMTP Errors

The SMTP errors that Gmail provides are key to mapping your path to getting off of Gmail’s blacklist.

For email delivery, the two main error codes are 421 and 550 errors.

421 Errors

421 errors are often temporary blocks. Most email servers will attempt to resend the email if they get a 421 error. If you quickly correct a spam or email flood issue, these blocks may resolve automatically. Left unchecked, Google may decide to block your email entirely.

550 Errors

550 errors are permanent failures. If you scan your logs for 550 errors from Gmail, they will often include links and additional information.

If you have 550 errors, you will likely need to take action before Gmail will remove your server IP address.

Requesting Blacklist Removal

Just so you know …  Google does not want you to contact them.

Their forms are buried behind a series our questions that typically lead nowhere. Most of the time you will start with Gmail’s “My domain is having delivery problems with Gmail” form. As you answer the questions, you will typically end up in a dead-end.

However, with the right sequence of answers, you can eventually wind your way to:

Report a delivery problem between your domain and Gmail.

This is where the action happens.   Complete the form in detail but do not be overly verbose.

Once submitted, you can expect it to take 3-7 days to process. Often, you will not hear back from Gmail. Your email will simply start flowing again – provided you fixed the reason you were blacklisted in the first place.

Bulk Senders

Sometimes you have a lot of email – legitimate email – to send. Google does not clearly define what is bulk email. Typically, you will see an SMTP error code in the 400 series, such as:

If you receive this message, be sure to review Google’s Bulk Sender Guidelines and then complete the Bulk Sender Contact Form.

Tricks to Getting Removed

We work on email delivery issues nearly daily. In our experience, if you do not fix these issues, your chances of getting removed from Gmail or any other blacklist is minimal.

• Reverse DNS Must Resolve to a Valid Hostname
• Your Server’s Hostname Must Have a DNS ‘A’ Record
• Do not blindly forward email to Gmail
• Make Sure DKIM/SPF are correct
• Stop the spamming!

You must make sure that whatever triggered the listing in the first place is stopped. If you  do not, you will simply be re-listed.

Get Help!

If all of this seems too much, then we can help.

Note that we have no formal relationship with Google or maintain their blacklist.