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GlockApps deliverability test guide and FAQ
Chris Traczyk avatar
Written by Chris Traczyk
Updated over a week ago

To test email deliverability we use the tool called GlockApps. It is the best tool out there for monitoring your deliverability and sender score. However, please remember that it's still not 100% foolproof.

What this app is testing is whether your messages are landing in the main folder or the SPAM folder, as there is no other direct way to check it. What GlockApps is doing is sending a bunch of messages to their email addresses located on different platforms (Outlook, Gmail, Yahoo) and checking where your messages landed.

You can perform the GlockApps test yourself for each email account in Settings->Integrations:

After the test is started a new tab will be opened where you'll see your pending test results! It usually takes 10-15 minutes for the test to be done.

We answered the frequently asked questions on this topic:

If any of the answers are unclear to you, or if you have any other questions regarding the GlockApps test and deliverability, please contact our Customer Support team!

1. What do the results mean?

At the top of the Deliverability tab, there is a diagram that shows the percentage of the messages that went to the Inbox, Tabs, Spam folders or were not delivered (missing) to the seed email addresses.


Inbox and SPAM rates are quite obvious, but there are also two more categories:

  • The Tabs rate shows the percentage of the messages that went to a tab in the Inbox, not to the general Inbox. It’s like the Promotions tab at Gmail or Newsletter tab or Commercial tab.

  • The Missing rate is the percentage of the messages that did not reach the test mailboxes. In the majority of cases, it is because the sending system did not send them or less frequently because the receiving server blocked or rejected the message.

NOTE: If your inbox placement rate is below 80% please please contact our Support Team to get help with improving these results. If your results are good and the only issue is deliverability to Outlook, there’s usually no need to worry. Outlook is a Microsoft offer for private clients. As you trying contact business clients they usually use Exchange as a Microsoft inbox.

2. What is Sender Authentication?

Authentication allows the mailbox provider to confirm that the sender is the one who he pretends to be. If authentication fails, the emails are likely to be filtered as spam or rejected.

Most important DNS records

  • SPF is a form of email authentication that defines a process to validate an email message that has been sent from an authorized mail server in order to detect forgery and prevent spam. The owner of a domain can identify exactly which mail servers they are able to send from with SPF protocols.

  • DKIM signature ensures that the message that arrives at the mailbox provider is identical to the message that you sent. DKIM protects the message against a malicious alteration in transit, and it is very important for reputation and deliverability because a valid DKIM record means that the sender takes responsibility for the content they send and the recipient to who they send it.

  • DMARC record - if the records described above are not enough, DMARC is built on top of them and adds additional features like reporting, policy definition, and the notion of identity alignment. Large mailbox provider email receivers, such as Google, Microsoft, and Yahoo!, require email messages to be properly authenticated in a DMARC-compliant way. So adding a DMARC record for a domain, in conjunction with properly configured SPF and/or DKIM records, will help ensure deliverability.

NOTE: You will find more detailed instructions on how to set up SPF, DKIM and DMARC in this article.

  • CNAME record is a type of record in the Domain Name System (DNS), that specifies that one domain name is an alias of another domain name. When you use our native click and open tracking, our system automatically changes your links a bit to see the prospect’s activity. As we don’t have direct access to your DNS records, these links by default are not associated with your domain. The CNAME record will allow you to customize them and is crucial if you want to keep your email deliverability perfect.

NOTE: You will find more detailed instructions on how to set up CNAME in this article.

Other records shown in the test results

  • rDNS-Reverse DNS lookup or reverse DNS resolution (rDNS) is the determination of a domain name that is associated with a given IP address. Some companies such as AOL will reject any message sent from a server without rDNS, so you must ensure that you have one (you cannot associate more than one domain name with a single IP address).

  • HELO is an SMTP command sent by an e-mail client when connecting to an e-mail server. The command tells the server that the client wishes to initiate an e-mail transaction and is followed by the client's domain name. The test of the HELO to IP checks if the name of your mail server successfully resolves to the server's IP address or not. If Outlook is your email provider, the test will be failed in the majority of cases. This is caused by their server configuration and cannot be fixed on your end.

  • What if HELO to IP was failed to authenticate?

    • You need to correct it. If you use your own SMTP server, then ask the server admin to do it. If you use an email service provider, please ask them to correct the issue. Email receivers can filter such emails as spam because they don't have trust in the sending server.

3. Why do my emails keep getting flagged as SPAM?

If you have the Email Authentication set up right, warmed up your email account, respect the email provider’s sending limits and you still get marked as SPAM it’s probably the issue with your Sender Reputation.

If the emails sent from your domain cause a negative user engagement, the reputation of the IP address won’t matter and the messages may be filtered by mailbox providers. Domain reputation can’t be built overnight, it takes time to establish one. You have to be careful and consistent in your sending habits.

Try to identify the probable causes - these two are the most common:

  • user complaints (very often on Gmail)

  • insufficient user engagement.

If you have a high spam complaint rate with Gmail, this is likely to be the root of any deliverability problems, because spam/abuse complaints submitted by email recipients are the primary significative the spam filtering system relies on.

A lot of various factors influence the deliverability of your emails, and the most important factor is how many people marked your email as SPAM vs. those who have replied or opened and Growbots can't influence that - only making sure you're sending relevant content to relevant people can.

Keep your engagement rate as high as possible, keep the emailing list clean by deleting inactive recipients and using segmentation (different campaigns for different target groups!), send relevant content, so that the unsubscribing rate isn’t high. This way you will avoid people flagging you as a SPAM sender!


4. What is a Sender Score?

The sender score is the sender's reputation. The main things that impacted it are SPAM traps and filtered messages (sent to SPAM or blocked). The higher the sender score, the better for deliverability. However, a high sender score doesn’t guarantee the Inbox placement, as it’s only the tool for allowing or rejecting the email. What is more important is the reputation of the sending domain and the sending IP address with the particular mailbox provider.

When you send the emails from a shared IP address(es), the sender score is calculated based on all messages sent by all the users sharing the IP. You don’t have much control over the sender score for shared IP addresses. If you send from a dedicated IP address, then you control all the email campaigns and the impact they have on the sender score.

The indices used to calculate the sender score are:

  • Prospect complaints

  • Daily sending volume

  • External Reputation

  • Unknown users

  • Rejected

If you want to find out more about the sender's score and its meaning, we recommend checking this article.

5. Why do my emails get sent from different IP addresses?

If you can see in your test results different IP addresses it means you have a shared IP. This is because your email provider uses shared IP addresses. A shared IP address is a domain that is used by multiple senders. Nowadays the majority of email providers such as Google or Outlook use it.


Can I get a private IP address?

The main criterion for making a decision is your size. If you are a large volume sender (sending more than 500,000 messages per month) and want to have complete control over your sender’s IP reputation, then you need to go with a dedicated IP address or even a few dedicated IP addresses.

If you are a small sender (sending fewer than 50,000 messages per month), you are good to stay with shared IP addresses.

6. How can I get off blacklists? Will it improve my results?

If you can see on the test results different IP addresses - blacklisting may not be connected with your email address in any way! You’re using public IPs and in this situation, a particular user doesn’t have that much impact on blacklisted IPs. From our experience getting off these blacklists won’t bring the expected results.

You’re sending messages from a variety of different IPs. These IPs are shared between multiple users of your email provider. One of these other users might be a spammer and this user’s activity will affect the IP reputation (which results in blacklisting this IP). You are sending messages from many different IPs and you don’t need to worry about some of them being blacklisted (many others aren’t :))

Getting off from these blacklists won’t bring any result as this IP might be blacklisted again in 2 days (by another user).

These IPs from the test have gotten blacklisted for thousands of users, so removing them on your end might not bring expected results. It depends more on your email provider side as they will probably remove this IP when they notice that it’s blacklisted.

Google's IP addresses don't have a bad reputation despite their listings in blacklists and sender scores.

NOTE: If you have a dedicated IP address please contact our Support Team to get help with getting off blacklists.

7. What are SPAM filters?


Spam filters are filters designed to sort emails according to certain criteria. When you send an email, spam filters decide where to place it: to the Inbox, to a special tab, to a spam folder, or block it altogether.

While Barracuda and SpamAssassin give a detailed report about how they assign the spam score, the Google Spam filter does not provide much information why it marked the message as spam and/or phishy. It returns only the final result.

8. What is the difference between interactive and non-interactive Gmail?

  • The "non-interactive" category includes Gmail email addresses where GlockApps does not mark the received messages as 'seen'. This group of test email addresses is useful when you send a cold email to new Gmail subscribers who have not interacted with your emails before.

  • The "interactive" category includes Gmail email addresses where GlockApps marks received messages as 'seen'. This group of email addresses helps test email deliverability with Gmail if your Gmail recipients have already interacted with your messages and showed a sort of positive engagement with your emails.

Ideally, your message should go to an Inbox with both groups of addresses. It would mean that your sender's reputation with Gmail is very good. When the sender's reputation is at the average or low level, Gmail looks at user engagement. Thus, you may see spam placements with non-interactive Gmail addresses.

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