Bounces processing

In email campaigns, a bounce occurs when an email fails to reach the recipient's inbox and is returned to the sender.

Un-deliverable, bounced or returned email are equivalent terms.
A soft bounce is also called transient or temporary.
A hard bounce is also called permanent.

nuevoMailer has a built-in bounces processor so you can process bounced emails resulting from your email campaigns when using your Host's smtp or your own smtp service.

In addition, you have dedicated webhook listeners to process bounces and complaints when using these 3rd party mail service providers.

Processing bounces with nuevoMailer

• You can add multiple bounce servers.
• You can connect an smtp server to a specific bounce server.
• You can initiate the processing manually or automate it using a cron job.
• It detects soft, hard bounces and automatic responses.
• Uncategorized emails and automatic responses can be deleted or moved to another mailbox folder so you can manually examine these emails.
• It extracts the related subscriber and campaign details, updates the campaign bounces report and the subscriber account.
• It does not automatically delete subscribers. You decide who/when to delete.
• But you can set thresholds for automatically suppressing subscribers.
• You can attach outbound webhooks to a bounce event so you can share/send this event data to external systems.
• Highly configurable: each un-deliverable email is scanned and compared to a collection of bounce reasons included in a simple xml file. A returned email may contain various descriptions (reasons) of why it bounced depending on the mail servers used in the communication process. You may edit this xml file, add more bounce reasons or change what should be regarded as soft or hard bounce. The most common bounce reasons and numeric error codes are already included in the file.
• Multi-language. The returned emails usually contain numeric error codes. But there are cases where such a code is missing and instead you find a bounce description in a language other than English. With this approach you can add your own bounce descriptions in the language of your choice in the xml file.

Webhooks for processing bounces and complaints when using 3rd party providers

When using 3rd party mail delivery services like Amazon SES, Mailgun and similar these providers take over the task of processing bounces and instead they can send notifications to nuevoMailer about these events: hard/soft bounce, delivery, complaint.

The user's guide provides detailed instructions on how to configure your provider.
nuevoMailer has dedicated webhook listeners for the following providers.

• Amazon SES/SNS
• Brevo / Sendinblue
• Mandrill / Mailchimp
• MailGun
• MailJet
• Mailersend
• Mailtrap
• Postmark
• SendGrid
• Smtp.com
• smtp2Go

What are the negative effects of high bounce rates

According to Amazon Simple Email Services guidelines, If your bounce rate is higher than 5-6% then you are in the danger zone of getting blacklisted.
This also applies to other major email services providers.

• Damage to sender reputation: email services providers track bounce rates and consistently high rates can lead to your emails being marked as spam or blocked altogether.
• Reduced deliverability: if your domain or IP gets flagged due to excessive bounces, future emails may find it difficult to reach your recipients' inboxes (even though they are valid).
• Waste of resources: sending emails that never reach recipients wastes your time, effort, and your marketing budget.
• Lower engagement: a high bounce rate means fewer people receive your emails, reducing potential interactions and conversions.

What are the benefits of processing bounced emails

By removing emails that bounce you maintain a clean and healthy mailing list. You will get fewer bounces in the next campaign. This is a virtuous cycle with interrelated positive effects.

• Improved key email marketing metrics meaning that your tracking reports become more accurate.
• Better engagement: by filtering out non-responsive addresses, you focus on recipients who are more likely to interact with your emails.
• Improved deliverability: ISPs do not like to receive emails that will bounce. Therefore you minimize the chances of having your IP or email getting blacklisted and thus having your newsletters rejected as spam.
• Safeguards your sender reputation which effectively results in your emails reaching subscribers' inboxes.
• Overall, your email marketing effort becomes more focused, effective and you make better use of your time and resources.

Cleaning up subscribers with bounces

• Automatic suppression based on thresholds is a very good approach to ensure that accounts that exceed these thresholds will always be excluded from all campaigns. But you also have more options:
• Every subscriber has two counters: soft and hard bounces. The processing only updates the related subscribers.
  You can then delete or suppress or set as un-confirmed the subscribers according to their soft/hard bounce values.
• It is not advisable to immediately update a subscriber whose email address soft-bounced once. Instead a good rule of thumb is to suppress subscribers having at least 2 soft bounces or 1 hard.
  By suppressing subscribers you still keep them in your system but exclude them from future campaigns.

Configuring bounces processing