The Email Marketing Stack
Copy, sending, automation, event data, and deliverability — the five layers of an email program that pays.
Email is a revenue line for you, not a newsletter habit. You need segmentation that reflects real behaviour, transactional mail that lands, and copy that ships weekly.
ChatGPT
Copy Production
9.1/10
beehiiv
Broadcast & Audience
9.0/10
Zapier
Integration Glue
9.4/10
Segment
Customer Data Layer
Mailgun
Transactional Delivery
Why These 5 Tools Work Together
Most email problems are not copy problems. They are data problems — you cannot segment on behaviour you never captured, and you cannot fix deliverability you never separated.
Split marketing and transactional sending. Marketing mail gets ignored and reported; transactional mail must arrive. Sharing a sending reputation between them is how password resets end up in spam.
Buy the event layer before you buy a more expensive ESP. Better data inside a cheap tool beats bad data inside an enterprise one.
The combined workflow: Segment captures behaviour across your product and site, that data flows into beehiiv audiences, ChatGPT writes the sequences and variants, Zapier connects anything without a native integration, and Mailgun carries transactional mail on its own clean reputation.
Who This Stack Is For
There is a point where email stops being a newsletter and starts being infrastructure. Usually it happens when someone asks why the abandoned-cart flow is not segmented by plan tier, or why password resets are landing in spam. That is the moment this stack makes sense. ChatGPT covers copy volume — subject lines, variants, flow sequences, the twelve small writing jobs that otherwise block a launch. Beehiiv handles broadcast and audience: the list, the site, the paid tiers, the referral loop. Segment sits underneath as the event layer, so behaviour from your product and site reaches your email tool in a shape you can segment on rather than as a mess of one-off integrations. Mailgun carries transactional mail — receipts, resets, alerts — on a separate reputation from marketing sends, which is the single most underrated deliverability decision most teams never make. Zapier stitches the parts that lack native connectors. Expect roughly $130-200/mo at modest volume, scaling with list size and event count. Every line item maps to a failure mode you have probably already hit.
How the Stack Fits Together
- 1. CaptureSegment
One event schema piped to every downstream tool.
- 2. Segmentbeehiiv
Audiences built on real behaviour, not signup date.
- 3. WriteChatGPT
Sequences, subject-line variants, and re-engagement copy.
- 4. ConnectZapier
The integrations nobody built natively.
- 5. DeliverMailgun
Receipts, resets, and alerts that land in the inbox.
Your Stack, Tool by Tool
A breakdown of each tool, what it does in this stack, and how to get started.
ChatGPT
Copy Production
Writes flows, variants, and subject lines at the volume email demands. Ten subject lines in twenty seconds is the difference between testing and guessing.
Key feature: Custom GPTs trained on your best-performing sends keep voice consistent across writers.
In this stack: Copy lands in beehiiv broadcasts and Mailgun transactional templates.
beehiiv
Broadcast & Audience
The marketing send layer: campaigns, automations, segments, a hosted site, and monetisation if the list itself is a product.
Key feature: Segmentation plus a referral engine and ad network in one subscription.
In this stack: Receives Segment audiences and Zapier-pushed events.
Zapier
Integration Glue
Fills the gaps between your CRM, billing, and email tools. Every email program eventually needs three integrations nobody built.
Key feature: Multi-step Zaps with filters and paths on paid plans.
In this stack: Bridges Segment, beehiiv, Mailgun, and whatever your billing system is.
Segment
Customer Data Layer
Collect events once and route them everywhere. Stops each tool having its own half-accurate version of user behaviour.
Key feature: One tracking plan feeding email, analytics, and warehouse destinations.
In this stack: Feeds behavioural traits into beehiiv segments and triggers Mailgun sends.
Mailgun
Transactional Delivery
API-first sending for receipts, resets, and alerts, with detailed logs and a sending reputation kept separate from marketing.
Key feature: Per-message event logs and dedicated IPs for teams that need them.
In this stack: Triggered by Segment events and Zapier; entirely separate from beehiiv sending.
What This Stack Costs
A clear breakdown of each tool's pricing for this persona.
| Tool | Free Plan? | Starting Price | Best Plan for Email Marketings |
|---|---|---|---|
| ChatGPT | Yes | Free / $20/mo | Plus ($20/mo) |
| beehiiv | Yes | Free / $39/mo | Scale (~$99/mo) |
| Zapier | Yes | Free / $19.99/mo | Professional ($49/mo) |
| Segment | Yes | Free / $120/mo | Team (~$120/mo) |
| Mailgun | No | $15/mo (10k emails) | Basic ($15-35/mo) |
| Estimated total monthly cost | $150 to $200/mo at moderate volume | ||
Prices as of April 2026. Most tools offer free trials.
Get Started in 30 Minutes
Sign up in this order to get the most value with the least friction.
- 1
Segment
Write a tracking plan first — 10-15 named events. Instrument those, then connect destinations.
- 2
Mailgun
Set up a transactional subdomain (mail.yourdomain.com) with SPF, DKIM, and DMARC before any send.
- 3
beehiiv
Import the list, warm the domain over two weeks, then build segments from Segment traits.
- 4
ChatGPT
Build a GPT loaded with your top 20 performing emails as the voice reference.
- 5
Zapier
Add integrations only where nothing native exists. Every Zap is future maintenance.
Swap-In Alternatives
Nothing here is sacred. If one tool does not fit how you work, these are the substitutions we would make.
beehiiv → Kit
Deeper lifecycle automation and creator commerce; less built-in monetisation.
beehiiv → ActiveCampaign
Best-in-class automation logic if flows matter more than publishing.
Mailgun → Brevo
Marketing and transactional in one bill, weaker log tooling.
Zapier → Make
Cheaper per operation once you run tens of thousands monthly.
Bonus Tools Worth Adding
Optional additions once the core stack is running smoothly.
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Who This Stack Isn't For
If any of these sound like you, a different Stack Pack will serve you better.
Solo creators sending one newsletter a week — this is over-engineered.
Check out The $50/Month Creator StackSales teams who need outbound sequencing and a CRM, not broadcast.
Check out The Sales Pro Stack