Bounce Management In Marketo – Top tips for bringing email bounces under control

Thankfully, Marketo has built-in tools for controlling bounces, differentiating between permanent and temporary bounces, and optimizing email deliverability. And with the right practices in place, it’s possible to keep your distribution list clean to ensure your messages reach the largest possible audience.

First, you need to distinguish between ‘hard bounces’ and ‘soft bounces’ because each type requires a different handling strategy:

• Hard Bounces: In these cases, the email didn’t reach the recipient due to a permanent issue, such as an invalid address (unknown user) or rejection by spam filters. Resending the email later will not resolve the issue, as it will continue to bounce. However, if the bounce is related to domain reputation issues, improving sender practices may increase delivery success in future sends. Hard bounce codes generally start with the number 5. For example, “name@kapturall.com 550 Message rejected.”

• Soft Bounces: Here, the email was sent to an active address but was temporarily rejected before reaching the recipient. Common reasons include temporary issues, such as the recipient’s server being offline or the mailbox being full, or volume limits that suggest slowing the send rate. In many cases, resending the message later may result in successful delivery. Soft bounce codes typically start with the number 4. For example, “name@kapturall.com 421 Try again later.”

Second, you need to understand the different codes that Marketo uses to report bounced emails. These bounce codes help identify the specific reason for each bounce and guide decisions on whether to remove or monitor a contact. Some common codes include:

• Code 550 (hard bounce): Indicates a definitive error, often because the recipient’s domain is nonexistent, or the address is invalid.

• Code 421 (soft bounce): Indicates a temporary issue, such as a full inbox or a server that couldn’t process the message.

Next, you need to understand how each type of email bounce needs a different strategy:

Hard bounces

Permanently removing or quarantining contacts with hard bounces prevents email providers from flagging your domain as a potential spam source. Regularly cleaning contacts with permanent bounces is crucial for resource optimization and delivery rates. In my experience, maintaining a clean, active contact list enhances open and click-through rates by avoiding sends to invalid addresses.

Soft bounces

A flexible strategy is more suitable for soft bounces, as they are usually temporary. However, if a contact accumulates multiple soft bounces, it’s advisable to place them in temporary quarantine or remove them from the distribution list to protect your domain’s reputation. Marketo allows for monitoring the recurrence of soft bounces to make targeted adjustments.

It’s possible to automatically track contacts with email bounces by creating a directory, in Marketo. This approach not only helps you identify problematic contacts, it also allows you to analyze specific bounce details. To do so, follow these steps.

1. Create 6 custom fields:

1. • DateTime Fields: Use ‘Bounce Date’ and ‘Email Delivered After Bounce’ to log the date of each bounce and when an email is successfully delivered after a bounce.

1. • Score Fields: Add ‘Email Bounces’ and ‘Deliveries After Bounces’ to count bounces and successful deliveries.

1. • String Fields: Include ‘Email Bounce Details’ and ‘Email Bounce Category’ to record the reason and category of the bounce.

2. Set up a program in Marketo:

1. • Create a program called ‘Directory Of Leads Bouncing Emails’ to house all elements and lists needed to manage bounced contacts.

3. Establish a static list:

1. • Create a static list called ‘Active Bounce List’ to store all leads with active bounces. This list will serve as your directory of bounced contacts and will update automatically.

4. Configure two smart campaigns:

1. • These campaigns will add or remove leads from the bounce list as bounces and successful deliveries occur.

Campaign 1 – Log bounces with bounce details

• Smart List: Use the triggers ‘Email Bounced’ and ‘Email Bounced Soft’ set to ‘is any’ to capture any email bounce.
• Flow Steps:

• • Step 1: Change the data value for ‘Bounce Date’ to {{system.dateTime}}.

• • Step 2: Change the data value for ‘Email Bounce Category’ to {{trigger.category}}.

• • Step 3: Change data value for ‘Email Bounce Details’ to {{trigger.details}}.

• • Step 4: Increase ‘Email Bounces’ score by +1.

• • Step 5: Add the lead to the ‘Active Bounce List.’

Campaign 2: Remove leads from list after successful delivery

• Smart List: Set a trigger ‘Email Is Delivered’ to ‘is any’ and add a ‘Member Of List’ filter to target leads in the static list.
• Flow Steps:

• • Step 1: Change the data value for ‘Email Delivered After Bounce’ to {{system.dateTime}}.

• • Step 2: Increase the ‘Deliveries After Bounces’ score by +1.

• • Step 3: Remove the lead from the ‘Active Bounce List’.

5. Create a custom list view to show bounce details:

1. • Custom fields don’t automatically appear in the list view. Create a custom view to display and export only bounce-related data, making it easier to identify trends and analyze deliverability issues.

This directory and these smart campaigns enable active, detailed monitoring of problematic contacts, helping optimize email deliverability in Marketo.

Effective bounce management is vital for protecting email deliverability and the sending domain’s reputation. Failing to manage bounces can lead to significant problems:

• With a dedicated IP, email providers may block your emails if your reputation drops too low, impacting all future campaigns​. 
• On a shared IP, poor list hygiene can harm the general IP reputation, risking penalties or even removal if sending practices are inadequate​. 

A robust bounce management strategy, including hard bounce removal, soft bounce monitoring, and updated directories, is critical for long-term email marketing success. 

Got a question about implementing a bounce management strategy in Marketo? We’re here to help. Get in touch with Kapturall today. Contact us