Summary
Determining if soft bounces were eventually delivered involves analyzing various data points as direct confirmation is often unavailable. Soft bounces are caused by temporary issues (full inbox, server down) and trigger automatic retries. Key indicators include examining email logs for 'delivered' events, monitoring SMTP codes for changes to '250 OK', analyzing trends in soft bounce rates, and tracking user engagement (opens/clicks) on previously soft-bounced emails. ESPs may define and report soft bounces differently, so understanding your ESP's specific practices is crucial. Delivery notification systems can also be used to check for a successful delivery.
Key findings
- Log Analysis: Examine email logs for 'delivered' events matching previous soft bounce attempts. Cross-reference using VERP when available.
- SMTP Codes: Monitor SMTP codes; a change from an error to '250 OK' indicates successful delivery after a retry.
- Bounce Rate Trend: A decrease in soft bounce rates over time suggests successful retries for a campaign or segment.
- Engagement Tracking: Monitor opens and clicks on emails that previously soft bounced; engagement suggests successful delivery.
- Delivery Notifications: Check for delivery notifications from your ESP or infrastructure provider, indicating the message was delivered successfully even after the initial soft bounce.
- Automatic Retries: Understand transient failures are retried, that's part of the normal email process.
Key considerations
- ESPs Definitions: ESPs may define and report soft bounces differently, impacting how you interpret the data.
- Data Availability: ESPs have delivery data but may not always make it available; inquire about access options.
- System Implementation: Implementing a system for tracking email delivery status can provide better insights.
- Monitoring: Constant monitoring is needed to identify trends and quickly react to delivery issues.
- Reporting Delays: Some ESPs may not report a soft bounce until after a certain number of failed attempts.
What email marketers say
8 marketer opinions
Determining if a soft bounce was eventually delivered requires analyzing email logs, SMTP codes, and engagement metrics. Direct confirmation is often unavailable, but examining delivery receipts, and a decrease in soft bounce rates over time, are good indicators. Tracking engagement (opens/clicks) on previously soft-bounced emails can also suggest successful delivery. Soft bounces indicate temporary issues like full inboxes or server problems, and servers should automatically retry delivery.
Key opinions
- Log Analysis: Examine email logs for 'delivered' events that match previous soft bounce attempts. Cross-reference using VERP when applicable.
- Bounce Rate Trend: A decrease in soft bounce rates over time suggests successful retries for a campaign.
- SMTP Codes: Monitor SMTP codes for changes from error codes to '250 OK,' indicating successful delivery.
- Engagement Tracking: Track opens and clicks on emails that previously soft bounced as indicators of successful delivery.
Key considerations
- Direct Confirmation: Directly 'telling' if a soft bounce was delivered is often impossible; rely on indirect indicators.
- Alternative Channels: Consider engaging subscribers through alternative channels if email delivery remains problematic.
- Automated Retries: Email servers automatically retry soft bounces; monitoring is crucial to understand delivery outcomes.
- System Implementation: Implement tracking systems to monitor delivery statuses after initial soft bounces.
Marketer view
Marketer from Email Geeks explains to look for a delivered event in your logs that matches the soft bounce and cross-reference in your own logs, especially when using VERP.
7 Nov 2021 - Email Geeks
Marketer view
Email marketer from Stack Overflow suggests implementing a system to track email delivery status. Check for 'delivered' receipts after the initial soft bounce. If a delivery receipt is found, the email was delivered after retries.
10 Feb 2022 - Stack Overflow
What the experts say
4 expert opinions
Determining if a soft bounce was eventually delivered involves understanding that ESPs may define and report soft bounces differently. ESPs possess data on delivery attempts, including retries, and their data availability should be investigated. Successful delivery attempts after initial soft bounces, opens, and clicks can indicate ultimate delivery. If the email is never delivered it will eventually turn into a hard bounce.
Key opinions
- ESPs Data: ESPs have delivery data, including retries; inquire about data availability.
- Delivery Indicators: Successful delivery attempts, opens, and clicks after soft bounces suggest eventual delivery.
- Retries: Temporary failures trigger automatic retries by the email server.
Key considerations
- ESPs Definitions: Soft bounce definitions vary among ESPs.
- Reporting Delays: ESPs may not report soft bounces until after a designated number of retries.
Expert view
Expert from Email Geeks shares her experience that many ESPs don’t report a soft bounce until delivery fails after the designated number of retries. They don’t report anything if it’s still in a queue.
4 May 2024 - Email Geeks
Expert view
Expert from Email Geeks shares that there is no universally accepted definition of a soft bounce, as ESPs use the term differently. ESPs have the data on whether a message was delivered, including delivery time and retries, so ask the ESP if they make that data available. Also advises to look for a successful delivery attempt to the same recipient from the same campaign to identify a retry being delivered.
18 Dec 2024 - Email Geeks
What the documentation says
4 technical articles
According to technical documentation, determining if soft bounces were eventually delivered involves actively monitoring delivery notifications and analyzing SMTP response codes. Transient failures, which trigger soft bounces, lead to automatic retries by the sending system. Successful delivery is indicated by receiving a '250 OK' SMTP response after a soft bounce, or by receiving explicit delivery notifications for previously soft-bounced addresses. Continuously monitoring these indicators is crucial for identifying delivery trends.
Key findings
- Delivery Notifications: Delivery notifications confirm successful deliveries, even after initial soft bounces.
- SMTP Analysis: A '250 OK' SMTP response following a soft bounce indicates successful delivery after a retry.
- Automatic Retries: Sending systems automatically retry delivery following transient failures that cause soft bounces.
Key considerations
- Configuration: Specific services may require configuration to receive bounce and delivery notifications.
- Continuous Monitoring: Ongoing monitoring of SMTP responses and delivery notifications is essential for identifying trends.
Technical article
Documentation from MailerQ explains that delivery notifications indicate successful deliveries. If a delivery notification comes after a soft bounce, it means that MailerQ has successfully delivered the message.
9 May 2024 - MailerQ Documentation
Technical article
Documentation from RFC 5321 explains transient failures include conditions such as "mailbox is full", "connection refused", or "server down". The sending system should retry delivery.
21 Sep 2024 - RFC 5321
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