What is the Gmail Blacklist?

As one of the most trusted email providers, Google keeps top-notch security by maintaining their own blacklist and security information. With the numerous users the company provides email accounts to, there is an overwhelming amount of data that Google can scrutinize for spam or malicious emails. By gathering this valuable information, rules are created to filter problem content. These rules are highly sophisticated, and as this data is compiled, specific IP addresses are flagged and sorted into what is called a blacklist.

The Gmail blacklist is designed to prevent unwanted spam, malicious content and excessive amounts of emails. Some of the most common reasons for getting blocked are as follows;

• Large amounts of emails sent from a new IP address.
• Sudden changes in email volumes.
• High bounce rates.
• Spam reports from Gmail users.
• Incorrect DNS settings.
• Low sender scores.
• IP listing in public blacklists.

Gmail’s blacklist may also take information from several public blacklists in order to block malicious/unwanted/compromised IP addresses prior to having any complaints from them. This is a preventative measure intended to keep the lowest amount of spam possible. All things considered, this is the reason your Gmail address will likely have far less unwanted emails or better filtering rules.

Why Should a Blacklist Matter?

There are several effects to being on the Gmail blacklist, and the most obvious is that all email from the IP address sending mail will be blocked. This means everything including personal communication, bulk messages, email lists, etc. Not only will it block the problem domain or user, but everything else on the SMTP server attempting to use that IP address.

This poses a large issue for shared IP addresses on any server. But there is hope! Both in the form of preventative measures as well as ways to redeem your IP address and clear it from the blacklist. Before clearing your IP address we highly suggest you review the information to make sure nothing has been compromised. Blacklists often mean an email has been hacked, or there are just poor emailing practices.

Preventatively, you can protect the IP you are using with SPF records should you have no current issues. These records will assist in providing additional verification for the IP address you are using and help keep your IP clean.

Need to Know about SPF Records?

If you’re already experiencing issues with Gmail delivery, then the first step is to diagnose the SMTP server. If this is a managed environment, it’s best to contact your hosting provider and ask them to review the specific email address having issues. Be sure to include example messages, any bouncebacks you’ve received and any specifics you can remember. (Subject lines, recipients, time of email, etc.) This should help in the retrieval of data.

You can actually get a full copy of the headers of any messages having issues directly from your email client. If you need information on how to do this, you can always check out this article. View full e-mail headers.

If you are having trouble delivering mail and can’t find any fault on your SMTP server, then it’s time to search some blacklists to test the waters. One of the most reputable places to start is mxtoolbox.com. Although Gmail does not state what mechanisms they use to blacklist, this site allows you to search your domain and query a large number of blacklists that should tell you if there are issues coming from your server. Along with cleanup instructions and links to each blacklist, this site is a handy tool for anyone looking to admin their own email.

There are several other sites that can be referenced for blacklist checking, but unfortunately, the only one way to get information from Google specifically. If you are not on a blacklist and there are no issues coming from the SMTP server, then it’s time to fill out a Delivery Problem Form. This form asks for basic information as well as any technical information you can provide. The more information you can provide, the easier your process will become for a listing check and possible removal or de-listing.

From there, Google should help you through the rest of the process or provide further information that will move the issues along. But that still leaves us with one question….

What are the Best Ways to Stay Off the Blacklist?

Well, the guidelines differ depending on what you are using email for. As some of us just use email for personal use the rules are pretty simple. Don’t send malicious content, make sure you don’t attempt to use huge files or send to everyone in your address book every thirty minutes for no reason, etc. These are all suspicious behaviors or hard rules that will either fail or cause issues.

Really we can boil the best practices down to a few important rules of thumb.

• Do not spam.
  • This includes redirects. Google has specific best practices for pulling email from other accounts, so setting up forwarders in other SMTP servers to shovel all mail over to Google addresses will simply count as spam.
• Follow the bulk mail guidelines.
• Pull, don’t push.
  • Meaning import messages or set Google to pull from third party, don’t forward to Google automatically. (Manual forwarding to share information is perfectly fine.)
• Use SPF records.
  • SPF records are great added security and verification.
• Change your passwords frequently.
  • Remember, passwords are vital and knowing the best practices for safe passwords is very important.
• Watch for, and read, bounceback emails.

Following the few suggestions above will keep your SMTP server healthy and happy. When all information intended for Google is pulled via their methods, the likeliness of being blocked for false positives (meaning blocked for legitimate practices done incorrectly) will go down exponentially.