Building an email stack when you're bootstrapped feels like a trap. You can spend $500/month on the "right" tools that marketing blogs recommend, or you can cobble together free tiers and hope nothing breaks. Neither path feels good. The expensive stack burns runway you can't afford. The free-tier patchwork creates technical debt that haunts you later.

There's a better approach: building a focused email stack that stays under $100/month at meaningful scale while still doing everything you actually need. Not what funded startups need, not what enterprise companies need—what you need as a bootstrapped founder who has to make every dollar count.

I've spent years watching bootstrapped companies either overspend on email infrastructure they don't need or underspend and regret it when deliverability tanks. This guide is the distillation of what actually works.

What "Email Stack" Actually Means for a SaaS

Before diving into specific tools, let's clarify what your email stack needs to do. The term gets thrown around loosely, but for a SaaS company, your email stack has to handle three distinct jobs:

Transactional emails are the system-generated messages your product sends automatically: password resets, email verification, payment receipts, usage alerts, and team invitations. These are non-negotiable. Your product literally doesn't work properly without them. They need near-perfect deliverability because users expect them immediately, and they're often tied to critical user flows.

Marketing emails are the campaigns and automated sequences designed to convert and retain users: welcome sequences, onboarding drip campaigns, feature announcements, upgrade prompts, and re-engagement emails. These drive the business outcomes you care about. They need good deliverability and the flexibility to personalize based on user behavior.

Newsletters and broadcasts are the one-to-many communications you send to your list: product updates, company news, educational content, and promotional announcements. These are important for relationship-building but typically lower priority than transactional and lifecycle emails.

Many bootstrapped founders make the mistake of treating these as separate problems requiring separate tools. At scale, that's sometimes true. At bootstrapped scale? You usually want one tool that handles all three, or at most two tools with clean separation.

The Stack Recommendation at Different Subscriber Levels

Here's what I recommend at each stage, with real monthly costs. These numbers assume you're sending reasonable volumes—roughly 4-8 emails per subscriber per month, which is typical for a SaaS with onboarding sequences, transactional emails, and occasional campaigns.

Subscribers	Recommended Stack	Monthly Cost	What You Get
0–1,000	Single platform (free tier)	$0–20	Basic automation, transactional, and campaigns
1,000–5,000	Single platform (paid tier)	$20–50	Full automation, segmentation, analytics
5,000–10,000	Primary + transactional backup	$50–80	Dedicated transactional path, full marketing features
10,000–25,000	Primary + transactional + analytics	$80–100	Scale-ready infrastructure within budget

Notice something about this table? At every level, you're under $100/month. That's not an accident. Staying lean on email infrastructure leaves budget for things that actually differentiate your product.

Stage 1: The $0–20/Month Stack (0–1,000 Subscribers)

At this stage, your goal is simple: don't overthink it. You need email working reliably so you can focus on building the product that will actually grow your business.

The single-tool approach works best here. Choose one email platform that handles transactional, marketing, and broadcast emails. Running multiple tools at this scale adds complexity without benefit.

Sequenzy (our platform, full disclosure) is free up to 1,000 subscribers and includes both transactional and marketing emails. The Stripe integration means your payment events automatically trigger the right emails without custom code. If you're building a SaaS with subscriptions, this is the relevant differentiator. If you're not monetizing through Stripe yet, this feature doesn't matter for you.

MailerLite offers a generous free tier up to 1,000 subscribers with good automation capabilities. It's more general-purpose than SaaS-specific, which can be a strength if you don't need deep product integration. The interface is clean, and the deliverability is solid.

Buttondown is worth considering if you're focused primarily on newsletters rather than product-triggered emails. It's simple, developer-friendly, and the free tier covers 100 subscribers with paid starting at $9/month for 1,000. Less automation, but if your email needs are primarily broadcast-style, it's elegant.

The honest trade-off at this stage: You're choosing between ease of integration with your product (Sequenzy) versus flexibility for non-SaaS use cases (MailerLite, Buttondown). Pick based on what you're actually building.

For transactional emails specifically, if your chosen marketing platform doesn't handle them well, Resend has a generous free tier (3,000 emails/month) with a developer-friendly API. This gives you a dedicated transactional path while keeping your marketing emails separate. But again, at this scale, running one platform for everything is usually simpler.

Stage 2: The $20–50/Month Stack (1,000–5,000 Subscribers)

You've hit the point where free tiers end and real decisions begin. This is also typically when your product has some traction, which means your email needs are becoming more sophisticated.

What changes at this stage:

Your onboarding emails should now be behavior-based, not just time-based. Instead of "Day 1, Day 3, Day 5" sequences, you want "signed up but didn't complete setup," "completed setup but didn't invite team," "invited team but hasn't used core feature." This requires your email platform to receive events from your product.

You probably have multiple types of users worth communicating with differently: trial users, paying customers, churned users who might come back. Basic segmentation starts mattering.

Your transactional email volume is growing, and deliverability matters more. One deliverability hiccup affecting password reset emails will generate support tickets.

The recommended approach:

Stick with a single platform if it's working. Sequenzy at $49/month handles up to 10,000 subscribers with full automation, behavioral triggers, and transactional emails through the same system. If you started on our free tier and it's working, there's no reason to add complexity.

ConvertKit at $29/month (up to 1,000, then $49 for 3,000) is a solid option if you're more creator/content-focused than product-triggered. The automation is good, but you'll need to build custom integrations for product events.

Customer.io starts around $100/month, which technically breaks our budget, but I mention it because it's the gold standard for behavioral email if you can stretch. If you're doing PLG and behavioral triggers are critical, it might be worth the premium. But for most bootstrapped SaaS, it's overkill at this stage.

The honest trade-off: Specialized SaaS email platforms (Sequenzy, Customer.io) make product integration easier but cost more than general-purpose tools. General-purpose tools (MailerLite, ConvertKit) are cheaper but require more custom development for behavioral triggers. If you're technical and have time, general tools plus custom code can work. If you'd rather pay for integration than build it, specialized tools make sense.

Stage 3: The $50–80/Month Stack (5,000–10,000 Subscribers)

This is the scale where cracks in your email infrastructure start showing. Deliverability issues that were invisible at 1,000 subscribers become painful at 5,000. Sequences that felt simple to maintain become a tangled mess.

What changes at this stage:

Transactional email volume is now significant. A dedicated transactional path becomes worth considering because it isolates your critical emails (password resets, payment confirmations) from any deliverability issues affecting your marketing sends.

Your subscriber list needs regular hygiene. Inactive subscribers hurt your sender reputation, and cleaning them is now a task worth doing monthly.

Analytics start mattering more. At 1,000 subscribers, you could track things in a spreadsheet. At 5,000-10,000, you need real analytics to understand what's working.

The recommended approach:

Primary marketing platform: $49–60/month. Sequenzy, ConvertKit, or ActiveCampaign for your marketing emails, automation sequences, and campaigns. Pick based on what you're already using that's working.

Dedicated transactional: $10–20/month. Move password resets, email verification, and payment receipts to a transactional-specific service like Resend, Postmark, or Amazon SES. These services optimize for deliverability and speed, not marketing features. SES is cheapest ($0.10/1,000 emails) but requires more technical setup. Postmark and Resend are more expensive but easier.

List hygiene: $10–20/month. A service like ZeroBounce or NeverBounce to verify your list quarterly. This catches invalid emails before they hurt your sender score. Budget $0.002–0.005 per email verified.

Why split transactional from marketing? Deliverability. Your marketing sends might occasionally trigger spam filters as you test subject lines and content. You don't want a spam complaint on a newsletter to affect whether password reset emails arrive. Separation creates isolation.

Stage 4: The $80–100/Month Stack (10,000–25,000 Subscribers)

At this scale, you're probably generating real revenue, which means email is now a meaningful business lever. You're still bootstrapped, but you're successful enough that slightly higher infrastructure costs are justified by business impact.

What changes at this stage:

You might need dedicated IP addresses for sending. Shared IP pools, which most platforms use, mean your reputation is partially determined by other senders. At this scale, the cost of dedicated IPs ($20–50/month) can be worth the control.

Segmentation becomes genuinely useful. You have enough subscribers that "trial users who haven't activated" and "customers on annual plans approaching renewal" are meaningful segments worth different messaging.

Testing delivers actionable insights. At 10,000+ subscribers, A/B tests actually reach statistical significance in reasonable timeframes.

The recommended approach:

Primary marketing platform: $49–79/month. Stay with what's working. Sequenzy's $49/month tier handles up to 10,000 subscribers with all features. At this scale, you might also look at ActiveCampaign ($79/month), which adds CRM features some teams find valuable.

Dedicated transactional: $15–30/month. Your transactional volume is now significant enough that you're past free tiers. Budget $15–30/month for a reliable transactional provider.

Analytics addition: $0–20/month. Your email platform's built-in analytics are probably sufficient, but if you want deeper insights, June.so or Mixpanel's free tier can help you understand how email campaigns affect product usage. Don't add this unless you'll actually use it.

Total: $80–100/month while handling email infrastructure that would cost $300–500/month if you'd started with enterprise tools.

Tools I'd Avoid (And Why)

Some tools that are popular in marketing circles don't make sense for bootstrapped SaaS:

Mailchimp is the default recommendation everywhere, but their pricing scales aggressively after the free tier, and the SaaS-specific features lag behind specialized tools. At 10,000 subscribers, you're looking at $150–200/month for their standard plan. You can do better for less.

HubSpot is a CRM that does email, not an email platform that does CRM. If you need HubSpot's CRM, use it for that and send email elsewhere. Their email features are mediocre, and the pricing is enterprise-focused.

Klaviyo is exceptional for e-commerce with Shopify integration but doesn't make sense for SaaS. The features are designed for shopping behavior, not product usage behavior. You'd be paying for capabilities you can't use.

SendGrid was once the default for transactional email, but deliverability has become inconsistent in recent years. Postmark, Resend, and Amazon SES are more reliable for pure transactional sending. If you're already on SendGrid and it's working, don't rush to switch. But if you're choosing fresh, there are better options.

Integration Matters More Than Features

Here's the truth that tool comparison charts won't tell you: the best email platform is the one you'll actually integrate properly. A mediocre platform deeply connected to your product beats a feature-rich platform that just sends broadcasts.

For SaaS specifically, integration means:

Your email platform knows when users sign up, what plan they're on, and what they've done in your product. Not just that they're a "subscriber"—but that they're a trial user who signed up yesterday, hasn't completed setup, and is on the Professional plan evaluation.

This requires either native integration (platforms like Sequenzy that connect directly to Stripe and common SaaS patterns) or custom development (piping events from your product to your email platform via API).

The time cost of integration is real. If you choose a general-purpose email platform, budget 10–20 hours of development time to connect it properly. If you choose a SaaS-specific platform with native integrations, budget 2–4 hours.

The honest calculus: If your product stack is unusual and native integrations won't help anyway, general-purpose tools make sense—you're building custom integration regardless, so choose on features and price. If your stack is standard (Stripe, common auth providers, typical SaaS patterns), platforms with native integrations save significant time.

When Sequenzy Is the Right Choice (And When It's Not)

Full transparency on our platform, since I'd want someone to tell me this:

Sequenzy makes sense if:

You're a SaaS using Stripe for payments. Our Stripe integration means subscription events (signup, upgrade, downgrade, churn, failed payment) automatically trigger the right emails without custom code. This is our core differentiator.

You want transactional and marketing emails in one place. We handle both, which simplifies your stack.

You need behavioral triggers tied to product events. Our API is designed for SaaS usage patterns.

You value direct founder support. We're bootstrapped too, and you'll talk to actual humans who built the product.

Sequenzy might not make sense if:

You're not using Stripe for payments. Our deepest integration is with Stripe. If you're using Paddle, LemonSqueezy, or custom billing, you lose the main differentiator.

You need e-commerce features. We don't do abandoned cart emails, product recommendations, or Shopify integration. If you're selling physical products, Klaviyo is better.

You need extensive template libraries. We're minimal by design. If you want hundreds of pre-built templates and drag-and-drop everything, MailerLite or ActiveCampaign have more polish.

You need a large team with role-based permissions. Our platform is designed for small teams. If you need elaborate approval workflows and granular permissions, enterprise platforms do that better.

We'd rather you choose the right tool than choose us for the wrong reasons. The worst outcome is you picking Sequenzy, realizing it doesn't fit, and having to migrate.

What a Complete $100/Month Stack Looks Like

Here's a specific example of what your email infrastructure might look like at 10,000 subscribers, staying under $100/month:

Primary email platform: Sequenzy at $49/month. Handles welcome sequences, onboarding automation, feature announcements, upgrade prompts, re-engagement campaigns, and most transactional emails.

Dedicated transactional backup: Resend at $20/month. Handles password resets and critical security emails through a separate sending path for deliverability isolation.

List hygiene: ZeroBounce for quarterly verification, roughly $20/month amortized ($60–80 per quarterly clean at 10,000 subscribers).

Total: $89/month for infrastructure that properly handles everything a growing SaaS needs.

Compare this to starting with Mailchimp ($150+), adding a transactional provider ($30+), and bolting on analytics ($50+), and you're at $230+/month for roughly equivalent capability. The bootstrapped stack isn't about doing less—it's about doing the same thing more efficiently.

Building for the Long Term

The stack I've described is designed to grow with you. At 25,000 subscribers, you might graduate to dedicated IPs and more sophisticated tools. At 50,000+, you're probably hiring email marketing help and can justify enterprise platforms.

But here's what matters: you shouldn't be planning your 50,000-subscriber stack at 1,000 subscribers. Build for your current stage, not for hypothetical future scale. The migration cost later is real, but it's a problem you want to have—it means you grew.

For deeper thinking on email costs and how they evolve, check out our guide on the true cost of email marketing for SaaS. And for strategies that respect bootstrapped constraints, our piece on email marketing for bootstrapped startups covers the mindset alongside the tactics.

Start Simple, Add Complexity When Earned

Here's the practical takeaway:

If you have under 1,000 subscribers: Pick one free-tier platform (Sequenzy, MailerLite, or Buttondown depending on your needs) and use it for everything. Spend zero dollars.

If you have 1,000–5,000 subscribers: Move to paid tier of your chosen platform. Budget $30–50/month.

If you have 5,000–10,000 subscribers: Add dedicated transactional sending and list hygiene. Budget $60–80/month.

If you have 10,000–25,000 subscribers: Optimize what you have, don't add more tools. Budget $80–100/month.

Every tool you don't add is complexity you don't manage, and money you keep for building your product. The bootstrapped email stack isn't about compromise—it's about focus.

Email infrastructure should be a solved problem, not an ongoing project. Set up something that works, automate what you can, and get back to building the thing that actually grows your business.