Causes of email delivery failure

When sending an email, some of them may not be delivered to the subscribers. This is because they are bounced or end up in the spam folder. In InSend you can see which emails were not delivered and why.

You can find the reasons for each email failure in the "Analytics" step. There are 3 types of failures: Email bounces, spam emails from the server and complaints from subscribers. To see a breakdown of the reasons for the failures, click on the corresponding number in the funnel and in the list on the right you will see the reason for failure for each email:

The table shows the reasons for the failures in the form in which the server sends them to us. Let us take a look at what it all means:

1. Rejected (bounced)

This section contains emails that the receiving server refused to accept for various reasons that have nothing to do with suspected spam.

2. Automatic spam reports

This section contains emails that the receiving server has refused to accept due to a suspicion of spam.

3. Complaints from recipients

This section lists emails that were delivered to the recipient's mailbox, but the recipient clicked the "This is Spam!" button in the mail service interface

It should be noted that for technical reasons not all complaints are delivered to InSend. This means that the actual number of complaints may be higher than the number displayed in the email analysis.

If your business needs to have the most accurate information about the number of complaints about your emails, we advise you to learn about the feedback loop mechanism. Please note that the configuration of this lies outside the area of InSend's responsibility and you will need to perform it yourself. To use it with InSend's emails, you will need to connect an additional "Dedicated IP address" package to your account.

Why some of the numbers on the funnel are not visible

In some cases you will notice that the numbers on the funnel in the newsletter do not match. For example: 100 emails were sent and 90 were delivered. At the same time, the "Rejected" and "Spam" reports do not show any emails; it is not clear where 10 emails "got stuck".

This is normal. It can be observed within 72 hours from the date of the email.

It is possible that some mail servers may delay or temporarily restrict delivery of your email for various reasons, responding with "try again later". In such a situation, InSend will attempt to send your letter 20 times within 72 hours. This process should end with either a successful delivery (the email appears in the "delivered" section) or a rejection (the email appears in the "rejected" section).

Recommendations for the elimination of errors

Error correction for "Rejected"

A large number of errors fall into the "Rejected" group - a good reason to think about how you capture your database and how you validate recipients' addresses.

Most likely, you will not check the validity of the address entered and immediately use it in your email. It is common practice to send an automatic confirmation email after a subscriber enters an email address. For example, when registering on the website, the user must activate their account by clicking on the link in such a confirmation email. In this way we get the guarantee that the email address is genuine, written without errors and belongs to this user.

If we talk about the methods of manual validation of an existing database, we can recommend the following steps:

1. Download all addresses with errors from InSend.

2. In the resulting file, carefully check the "Email" column and try to eliminate the following common errors:


(a) errors and typos in the addresses of known mail servers:


  • lizst.com - list.com
  • gmail.hu - gmail.com
  • etc.

3. The corrected addresses can be loaded back into InSend using the "Audience" interface. This process is described in detail in the article How to import my recipient list.

Reducing the number of automated spam reports and complaints

A large number of spam reports indicates that your emails look like spam to the mail servers.

When dealing with complaints, the above recommendations are also very useful.

Try to understand what exactly caused the recipient to mark your email as spam. Maybe you send emails too often. Or your emails look like spam. Or the user has not agreed to receive emails from you.

One of the most effective ways to reduce the number of complaints is to confirm the subscription (double opt-in). In many countries, this process is required by law for all mailings.

The ban on resending emails to rejected addresses

InSend does not resend emails to addresses that have ever fallen into the "Rejected" group. However, these appear in the statistics of the emails and thus reduce the overall percentage of conversions.

To solve this problem, you can unsubscribe such email addresses from all your emails in your InSend account. Unsubscribed addresses will then no longer appear in the statistics for the emails.

To do this, prepare a file with a list of addresses and upload it to InSend, as described in the How to download or upload a blacklist of unsubscribed customers article.

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