Nonprofit Migrates from Mailchimp to HubSpot with Deliverability-First Strategy

Organization type: Statewide nonprofit

Email List Size (Before): 18,000 contacts

Email List Size (After Cleanup): 13,000 qualified contacts

Primary Goal: Migrate to HubSpot without damaging deliverability

Secondary Goal: Stay within marketing contact limits while improving list health

Platform Migration: Mailchimp → HubSpot

Automation Consolidated: Mailchimp + Flodesk → Native HubSpot workflows

This nonprofit was sending monthly emails to a large list built over time in Mailchimp.

However, the list had:

• 18,000 total contacts
• Overlapping segments 
• Historical tagging clutter
• No centralized engagement filtering
• Limited visibility into per-contact activity
• Multiple tools handling automation

Moving everything into HubSpot without a strategy would have:

• Increased marketing contact costs
• Risked email deliverability issues
• Damaged sender reputation during platform transition
• Imported unnecessary legacy data

Additionally, because they send primarily monthly emails, warming up a new sending server required careful planning.

18,000 → 13,000 engaged contacts migrated
5,000 unengaged contacts intentionally excluded
Improved sender reputation protection
Reduced marketing contact costs
Subscription types properly structured
Email automation consolidated inside HubSpot
Deliverability-first warm-up plan implemented

Instead of blindly importing the full list, the organization now has a healthier, engagement-based email system designed for long-term growth.

This approach works well for nonprofits and associations that:

• Are migrating from Mailchimp to HubSpot
• Have large legacy lists with mixed engagement
• Want to protect deliverability during transition
• Need to stay within marketing contact limits
• Send primarily monthly emails
• Use multiple disconnected email tools
• Care about long-term CRM health