Understanding and managing email bounce in SystemeScale

The purpose of this article is to clearly define the concept of an email bounce, a critical metric for deliverability.

We will explain the mechanisms behind bounces, the distinction between hard bounces and soft bounces, and their impact on sender reputation.

1. What is an email bounce?

An email bounce occurs when an email is not delivered to an email address. In such cases, the sender can often view which contacts did not receive the message, either in the email statistics or in each contact’s email history.

This failure comes from the recipient’s mail server for various reasons. The email address may be invalid or no longer exist, often due to a typing error or an old contact base. In other cases, it may be a temporary problem, such as a full inbox or an unavailable server. It can also happen when anti-spam filters on the recipient’s side block the message.

A high bounce rate is an important indicator of a list quality problem. It often reflects an outdated, poorly maintained, or insufficiently verified contact base.

Mail providers like Gmail and Outlook closely monitor this type of signal to evaluate sender reliability. If you frequently send emails to invalid addresses, you may progressively be considered a risky sender.

This damage to your reputation has direct consequences: your emails are more likely to be redirected to the spam folder or blocked before reaching recipients.

2. Categories of bounces

In SystemeScale, there are two categories of bounces you may encounter: soft bounces or blocks and hard bounces.

Soft bounces should be considered temporary blocks. It is not necessary to permanently remove those email addresses from your contact list.

Hard bounces refer to permanent delivery failures. This means the email address is invalid, non-existent, or permanently unavailable. In this case, it is important to immediately remove or stop sending to those addresses because continuing to email them directly harms sender reputation.

You can identify bounce types in your statistics:

• An address shown in gray indicates a hard bounce. The email could not be delivered and is not expected to be delivered in the future.
• An address shown in blue and clickable indicates a soft bounce, meaning a temporary failure such as an unavailable server.

Blue addresses remain active in your contact list because future delivery may work and the contact record remains available.

Soft bounce

A soft bounce means the recipient’s email address is valid and the message reached the recipient’s mail server, but it was rejected before being delivered to the inbox.

SystemeScale does not mark the contact as bounced in your contact list because the rejection only applied to that specific message.

Common reasons for a soft bounce include:

• The recipient’s server is temporarily unavailable
• SMTP server not responding
• Blocked IP address
• Blocked domain or blacklisting
• Content or links flagged as suspicious or spam

Hard bounce

A hard bounce means the email was permanently rejected.

This can happen for one of the following reasons:

• The email address is invalid
• The email address does not exist
• The recipient’s inbox is full and delivery cannot be completed

How SystemeScale handles hard bounces

SystemeScale handles hard bounces in two ways.

1. Bounced status in the contact list

If an email address is marked as bounced in your list, future emails to that contact will not be attempted. This protects your deliverability because continuing to send to bad addresses harms your sender reputation.

2. Fake or non-existent addresses

Fake or non-existent addresses may be automatically removed from your contact list once identified as fake or deactivated.

3. How to improve your email bounce rate

Reducing your email bounce rate is essential to ensure your messages reach your audience and generate positive engagement.

• Regularly clean your email lists: Remove invalid, inactive, or unengaged addresses to maintain list quality and reduce bounces.
• Use double opt-in forms: Ask subscribers to confirm their subscription through a link sent by email. This helps ensure only real, interested subscribers join your list.
• Add reCAPTCHA to your forms: This prevents bots from subscribing and adding bad contacts to your list, even if you already use double opt-in.
• Personalize your emails: Use subscriber data such as interests, behavior, or purchase history to create tailored content.
• Send emails consistently: If you have not contacted your list in a while, some addresses may no longer exist, resulting in hard bounces.
• Segment your list: Divide your list based on criteria such as location, preferences, or behavior. Relevant content can reduce bounces and improve engagement.
• Use email verification tools: Before sending, check your list with verification tools to detect and remove invalid or inactive emails.
• Avoid spam-like words and practices: Avoid excessive capitalization, exaggerated claims, overly frequent sending, and suspicious-looking links.
• Encourage engagement and replies: Include clear and relevant calls to action that invite clicks, replies, and interaction.

By following these tips and monitoring your email performance metrics closely, you can significantly lower your bounce rate. This helps maintain a clean and reliable contact list, improves deliverability, and increases the overall effectiveness of your emails.

Related deliverability guides

Use the related guides below to improve deliverability, authenticate your domain, clean your list, and manage bounced contacts.