Bounce Monitoring Workflow

Protect your email sender reputation with automated bounce detection and suppression. This workflow catches bounces as they happen rather than waiting for periodic cleanup.

How It Works

Prerequisites

• HubSpot Marketing Professional or Enterprise plan
• A HubSpot private app access token (HUBSPOT_ACCESS_TOKEN in .env) with the automation scope (for the API path)
• Python 3.10+ with uv
• A custom contact property for review flagging (default: email_health_flag — the execute script creates it if missing)
• Admin email or Slack channel for hard bounce alerts

Scripts

before.py inventories existing workflows and checks name collisions. execute.py creates the email_health_flag property (if missing) and three bounce workflows via POST /automation/v4/flows — always disabled, for review before enabling. after.py verifies and reports enabled state.

Building the Workflow: Two Options

Option A: Create via the v4 Automation API (primary)

Instead of one workflow with three nested branches, the script decomposes the design into three linear workflows — the same coverage, cleanly expressible via the API and independently tunable:

1. Hard Bounce Suppression: enrollment = hs_email_hard_bounce_reason_enum is known. Actions: set email_health_flag, set marketing contact status to non-marketing.
2. Suppress at N+ Bounces: enrollment = hs_email_bounce >= suppression threshold (re-enrollment on). Action: set marketing contact status to non-marketing.
3. Flag for Review at M+ Bounces: enrollment = hs_email_bounce >= review threshold (re-enrollment on). Action: set email_health_flag (feeds /review-bounced-contacts).

Configure SUPPRESSION_THRESHOLD and REVIEW_THRESHOLD in execute.py, then:

uv run skills/bounce-monitoring-workflow/scripts/before.py
uv run skills/bounce-monitoring-workflow/scripts/execute.py

Safety model: all three workflows are created with isEnabled: false. During UI review: add the internal-notification actions (hard bounce alert, review alert — notification recipients are portal-specific), add “Set marketing contact status” manually if the script reported it had to omit it, then turn the workflows on.

Option B: Manual UI Build (single workflow with nested branches)

Follow the step-by-step instructions in Stage 3 below — the original single-workflow design with three branch levels. Use this on portals where the Automation API is unavailable.

Alternatives: HubSpot Breeze AI can scaffold a similar workflow from a prompt, but it creates event-based (OR) triggers, cannot configure re-enrollment, and may flatten nested branches — verify everything it builds. The Claude Chrome extension can drive the workflow builder UI directly. Both are secondary options.

Step-by-Step Build Instructions

Stage 1: Plan

1. Choose your suppression threshold (commonly 2-3 bounces) and review threshold (commonly 3-5).
2. Decide who receives hard-bounce and review alerts.

Stage 2: Before

1. Run uv run skills/bounce-monitoring-workflow/scripts/before.py to inventory workflows and check name collisions.
2. Identify your current bounce baseline — run a quick search for contacts where hs_email_bounce > 0 to understand the starting volume.
3. If building manually, create your bounce review property (checkbox or dropdown) — the API path creates it automatically.

Stage 3: Execute

Option A: run uv run skills/bounce-monitoring-workflow/scripts/execute.py, then complete the UI review steps listed above.

Option B — manual UI build: build a single contact-based workflow with branching logic.

1. Trigger: hs_email_bounce is known (fires when bounce count updates)

2. Branch 1: Hard bounce check

   • Condition: hs_email_hard_bounce_reason_enum is known
   • YES:
     • Send internal notification: “Hard bounce: {email} — {hs_email_hard_bounce_reason_enum}”
     • Set hs_marketable_status to non-marketing (workflow action)
   • NO: Continue to Branch 2

3. Branch 2: Bounce count >= your suppression threshold (commonly 2-3)

   • Condition: hs_email_bounce is greater than or equal to your suppression threshold
   • YES:
     • Set hs_marketable_status to non-marketing (workflow action)
     • Continue to Branch 3
   • NO: No action (below threshold — monitor only)

4. Branch 3: Bounce count >= your review threshold (commonly 3-5)

   • Condition: hs_email_bounce is greater than or equal to your review threshold
   • YES:
     • Set your bounce review property = flagged
     • Send internal notification: “Contact {email} has [review threshold]+ bounces — review for deletion”
   • NO: No further action

5. Settings:

   • Re-enrollment: ON (contact should re-enter if bounce count increases)
   • Goal: None

6. Turn on the workflow.

Stage 4: After

1. Run uv run skills/bounce-monitoring-workflow/scripts/after.py (API path) to confirm the workflows exist and report enabled state.
2. Check workflow history after the first week of email sends.
3. Review the flagged contacts list weekly — decide for each contact:
   • Delete if the email is clearly invalid (typo domain, defunct company)
   • Attempt recovery if the domain is valid (could be a temporary mailbox issue)
4. Monitor overall bounce rate in HubSpot email health dashboard.

Rollback

1. Turn off the workflow.
2. Contacts already suppressed remain non-marketing. To reverse:
   • Filter contacts suppressed by this workflow (check your bounce review property or workflow history)
   • Manually set back to marketing contacts in the UI
3. Clear your bounce review property values in bulk if needed.

Weekly Review Process

For contacts flagged at your review threshold:

1. Export the flagged contacts list.
2. For each contact, check:
   • Is the email domain still active? (Quick MX record check)
   • Is this a known customer or high-value contact?
   • Was the bounce recent or historical?
3. Delete contacts with invalid domains or clearly fake emails.
4. Keep suppressed contacts with valid domains but repeated soft bounces.
5. Clear the bounce review property after review.