Bounce Status and Deliverability Guide

To optimize our email marketing campaigns and protect our sending IP reputation, Webmecanik and Mailjet categorize every delivery failure using a precise typology. Here is how to interpret these different blocks.

1. Permanent Blocks (Hard Bounces)

These statuses indicate that the email address is permanently invalid or closed. Platform Action: Mailjet and Webmecanik automatically exclude these contacts from future mailings to prevent any degradation of our sender score.

• User unknown: The destination server confirms that this email address no longer exists. In a B2B context, this typically happens when an employee has left the company and their mailbox has been deleted.

• : (Non-existent address): A critical identification error. The address could not be resolved or simply does not exist on the receiving server.

• Typofix (Domain error): The email domain contains an obvious syntax error (e.g., gamil.com instead of gmail.com). The platform blocks the email before sending to avoid an unnecessary bounce.

• Spam (Spam Complaint): The recipient clicked the "Report as spam" button in their email client. This is a highly negative signal for deliverability. Mailjet treats this action as a permanent block for this contact.

2. Temporary Blocks (Soft Bounces)

The email address is valid, but the message could not be delivered due to a temporary hurdle on the recipient's end.

• Quota exceeded (Full mailbox): The recipient's inbox is saturated and can no longer receive messages. Nowadays, this usually points to an abandoned email account.

• Connection issue: The receiving mail server was temporarily unreachable (network outage, maintenance, or overload on their end) at the exact time of the delivery attempt.

3. System and Behavioral Blocks

These statuses result from either platform security rules or explicit user actions.

• Preblock (Mailjet Pre-blocking): This is Mailjet’s proactive shield. If an email address recently generated a Hard Bounce with another client on the Mailjet network, the platform blocks your email before it is sent. This instantly safeguards your sender reputation without negatively impacting your stats.

• User (Manual Unsubscribe): The contact opted out voluntarily (either via the unsubscribe link in the email or through a manual action inside Webmecanik). The email address is technically fine, but you no longer have the legal consent to contact them.

⚙️ Contact Management Automation Rules

Here is the strict logic applied by the application to automatically handle these different statuses and maintain clean database hygiene:

• Hard bounces ➔ Block immediately ❌

  As soon as a permanent bounce is detected (User unknown, :, Typofix), the contact is instantly excluded from future mailings to protect the IP reputation.

• Soft bounces ➔ Track and allow 5 attempts before blocking 🔄

  In line with market standards, the application tracks the contact's history. A grace period of 5 consecutive attempts (for temporary failures like Quota exceeded or Connection issue) is granted. If the issue persists past the 5th attempt, the contact is blocked.

• Unsubscribes ➔ Respect choice and block immediately 🛑

  The moment a user clicks the unsubscribe link (User), their choice is applied instantly. They are automatically restricted from receiving any future marketing communications.

• Spam reports ➔ Block immediately to protect reputation 🛡️

  To avoid being blacklisted by ISPs and webmail providers (Gmail, Outlook, Yahoo...), any "Spam" report triggers an immediate and permanent block of the contact.

Bounce Management Reference Table

💡 Expert Tip: A high rate of Preblock or User unknown statuses during a campaign is a symptom of an aging or poorly qualified database. If these metrics spike, it's high time to review your Double Opt-In workflows or run a thorough database cleaning campaign.