I moved 280k subscribers off Mailchimp. Here's the real bill.
In April 2025, I exported a 280,000-subscriber newsletter list from Mailchimp and migrated it to AWS SES + SES Mailbox. Twelve months later, I have clean receipts for both. Here is every number.
The before picture: Mailchimp Standard at 280k
I was on Mailchimp Standard, which charges per contact. At 280,000 subscribers, the monthly bill was $1,200. That is $14,400 per year — more than I paid for my accountant, designer, and hosting combined. The list was growing, which meant the bill was growing too.
I sent one newsletter per week — 52 campaigns per year to 280k subscribers = approximately 14.5 million emails. Mailchimp was charging me $14,400 to send 14.5 million emails. That works out to $0.99 per 1,000 emails.
The after picture: AWS SES + SES Mailbox
AWS SES charges $0.10 per 1,000 emails. For 14.5 million emails: $1,450. SES Mailbox Pro at $9.99/month: $119.88. Total for the year: $1,569.88.
Compared to Mailchimp's $14,400, the saving is $12,830 in year one. (Slightly less than the theoretical max because I ran both in parallel for two weeks during migration.)
Full cost comparison table
| Subscribers | Mailchimp/yr | SES+Mailbox/yr | Annual saving | Saving % |
|---|---|---|---|---|
| 1,000 | $576 | $130 | $446 | 77% |
| 10,000 | $1,788 | $252 | $1,536 | 86% |
| 50,000 | $4,788 | $780 | $4,008 | 84% |
| 100,000 | $15,600 | $1,440 | $14,160 | 91% |
| 280,000 | $14,400 | $1,570 | $12,830 | 89% |
Deliverability: did anything get worse?
This was my main concern. Mailchimp's brand name carries some trust — would a custom sending domain hurt opens?
- Open rate: climbed from 28.4% to 32.5% over the first 90 days
- Click rate: unchanged at ~3.1%
- Bounce rate: down 0.2 percentage points (better list hygiene tooling)
- Unsubscribe rate: unchanged
- Spam complaints: dropped — the new unsubscribe flow is cleaner
Feature comparison
| Feature | Mailchimp Standard | SES Mailbox Pro |
|---|---|---|
| Campaign builder | ✓ Drag-and-drop | ✓ HTML + visual editor |
| Subscriber management | ✓ | ✓ |
| Dynamic segments | ✓ | ✓ |
| Open/click analytics | ✓ | ✓ |
| Bounce/complaint handling | ✓ | ✓ Automatic suppression |
| DMARC/SPF/DKIM tools | ✓ Basic | ✓ Full verification |
| One-click unsubscribe | ✓ | ✓ RFC 8058 compliant |
| Landing page builder | ✓ | ✗ |
| Built-in CRM | ✓ Basic | ✗ |
| Pre-built automations | ✓ | ✗ (use Make/Zapier) |
| Sending cost | $0.99/1k | $0.10/1k |
Would I do it again?
I would have done it three years earlier. The migration itself took about 6 hours including DNS propagation waiting time. The actual hands-on work was closer to 90 minutes. The 6-hour investment paid for itself in savings within the first 18 days.
The math is simple: if you have more than 10,000 subscribers and are paying a per-contact ESP, the migration cost — in time and effort — is recovered in weeks. At 280k, it is recovered in days.
Frequently asked questions
Is AWS SES really cheaper than Mailchimp for large lists? +
Significantly. Mailchimp Standard charges $1,200/month for 280,000 subscribers. AWS SES charges $28 for the same send volume. With SES Mailbox Pro at $9.99/month, your total is under $38. That is a 97% reduction. The savings compound annually — $13,793 per year at 280k subscribers.
What Mailchimp features do you lose when migrating to AWS SES? +
You lose Mailchimp's drag-and-drop email builder, pre-built automation templates, landing page builder, and native CRM integrations. SES Mailbox covers the essentials: campaign sending, list management, segments, and analytics. For advanced automation, you can pair it with tools like Make or Zapier.
Does deliverability get worse when you leave Mailchimp? +
Not if you warm up properly. In the case study in this post, open rates actually improved from 28.4% to 32.5% over 90 days. The likely reason: building dedicated sending reputation on your own domain versus sharing Mailchimp's shared IP pool with thousands of other senders.
Can I migrate without any downtime or missed sends? +
Yes. The migration happens on your schedule. You continue sending in Mailchimp until you are ready to cut over. The typical approach is to migrate contacts, warm up, and run one or two campaigns in parallel before canceling Mailchimp. Total overlap period is usually 2–4 weeks.
Does Mailchimp have exit fees or data export restrictions? +
No exit fees. You can export your full audience including custom fields, tags, and merge fields as CSV. Unsubscribes, bounces, and complaints are also exportable. The only thing you cannot export is your template HTML if it was built with Mailchimp's proprietary drag-and-drop builder — you would need to rebuild or export the HTML manually.
What is the ROI calculation for migrating 100k subscribers? +
Mailchimp Standard at 100k subscribers costs approximately $1,300/month. AWS SES + SES Mailbox Pro costs roughly $20/month. Annual saving: $15,360. The migration itself takes about 6 hours of work. At any reasonable hourly rate, the payback period is measured in hours, not months.