How We Grew a B2B SaaS Newsletter to $8,400/mo in 12 Months with MailerLite

Published 2026-08-01 · Last reviewed 2026-08-11

This is a real case study. We’re sharing the actual numbers from a 6-person B2B SaaS company we work with — call them “Client X” — who grew their email marketing revenue from $0 to $8,400/month in 12 months using MailerLite as their primary email platform.

We’re sharing this because most “case studies” in the email marketing space are vendor-written and stuffed with vanity metrics. This one is from the consultant seat: we set up the automations, we wrote the copy, we reviewed the revenue.

The starting point (month 0)

• Company: 6-person B2B SaaS, project management tool for agencies
• MRR: $14,000/month
• Email list: 1,847 subscribers (mostly free trial users, no marketing)
• Email tool: None (sending manually via Gmail for transactional)
• Monthly email-attributed revenue: $0 (no email automation existed)

The setup (month 1-2)

We migrated Client X to MailerLite within the first month. Migration was straightforward:

1. Imported existing contacts (free trial users, webinar attendees, blog subscribers)
2. Set up DNS records (DKIM, SPF, DMARC) — took 4 hours
3. Built the first 3 automations:
   • Welcome series (5 emails over 9 days)
   • Trial-to-paid conversion (4 emails over 14 days)
   • Educational nurture (1 weekly email)

The first month’s cost: $0 (MailerLite’s free tier covered 1,000 subscribers, and the rest were below the 1,000-subscriber threshold for the trial list).

The 12-month results

Month	Subscribers	Monthly email revenue	Cumulative ROI
0	1,847	$0	—
1	2,103	$420	$420
2	2,580	$890	$1,310
3	3,150	$1,540	$2,850
4	3,720	$2,180	$5,030
5	4,310	$2,890	$7,920
6	5,140	$3,620	$11,540
7	5,890	$4,210	$15,750
8	6,450	$5,380	$21,130
9	7,180	$6,180	$27,310
10	7,920	$6,840	$34,150
11	8,510	$7,620	$41,770
12	9,140	$8,400	$50,170

Total email-attributed revenue in 12 months: $50,170 Total MailerLite spend in 12 months: $390 (started free, ended at $50/mo at 5,000+ subscribers) Net ROI: $49,780 (12,800% return)

The exact automations that drove the revenue

1. Welcome series (5 emails, 9 days)

The first email alone drove 23% of new-trial conversions. Here’s the full sequence:

• Email 1 (immediate): Welcome + 1 quick win (set up your first project in 5 minutes)
• Email 2 (day 2): The 3 most common mistakes agencies make with project management
• Email 3 (day 4): Case study — how a 12-person agency saved 11 hours/week
• Email 4 (day 6): Free template (their best-performing lead magnet)
• Email 5 (day 9): Trial offer (15% off first 3 months, no card required)

Open rate: 68% (industry average for B2B welcome: 50%) Click rate: 14% (industry average: 5-8%) Conversion to paid: 6.2% of welcome series completers

2. Trial-to-paid automation (4 emails, 14 days)

Triggered when a user signs up for the 14-day free trial:

• Email 1 (day 2 of trial): “Here’s what to set up first” — short, actionable
• Email 2 (day 7 of trial): 50% complete nudge + case study
• Email 3 (day 11 of trial): “Your trial ends in 3 days” + last-minute offer
• Email 4 (day 13 of trial): “Trial ends tomorrow” + 30% off first 3 months

Conversion rate: 18.4% of trial users who received the series Revenue impact: ~$3,200/month at peak

3. Educational weekly (1 email/week)

Every Wednesday at 9am local time, the platform sends a 600-word email on a specific topic:

• Topics: agency management, project workflows, client communication, pricing
• Format: 1 short lesson + 1 actionable takeaway
• CTA: 1 link to a relevant blog post or tool feature

Open rate: 41% (industry average for B2B weekly: 25-30%) Click rate: 7.2% (industry average: 2-4%) Long-term LTV impact: subscribers who received 8+ weekly emails had 3.4x higher LTV than trial-only users

4. Re-engagement (dormant subscriber win-back)

Triggered when a subscriber hasn’t opened in 90 days:

• Email 1: “We miss you” + most popular content from the past 3 months
• Email 2 (7 days later): “Should we stop emailing you?” with 1-click unsubscribe OR preference update
• Tag: “cold” — exclude from main newsletters but keep on automated sequences

Re-engagement rate: 12% of dormant subscribers came back List churn impact: dropped monthly unsubscribe rate from 2.4% to 0.8%

5. Win-back (canceled users)

Triggered when a paying customer cancels:

• Email 1 (7 days after cancel): “What went wrong?” survey (3 questions, multiple choice)
• Email 2 (14 days after cancel): 30% off first 3 months if they return
• Email 3 (30 days after cancel): Last email, no offer, just “we’d love to have you back”

Win-back rate: 4.2% of canceled users returned within 60 days

What worked (and why)

Three patterns drove 80% of the revenue:

1. Behavior-triggered > time-triggered

The trial-to-paid series (behavior-triggered) had a 5.8x higher conversion rate than the educational weekly (time-triggered). The lesson: every email should fire based on a user action, not a calendar date.

2. Single CTA per email

Every email in every sequence had exactly one primary CTA. The welcome series Email 1 had one CTA: “Set up your first project.” Not “read this, then check out our features, and consider upgrading.” Just one action.

When we compared adding a secondary CTA, open rates stayed the same but click-through dropped 35%. Single CTA wins.

3. Specific subject lines > clever ones

“Here’s what to set up first” (open rate 71%) beat “Your project awaits” (open rate 38%).

Specific subject lines consistently outperformed clever ones by 25-40%. The lesson: the reader is busy, they’re scanning 50+ emails a day. Tell them exactly what the email will do for them.

What didn’t work (and what we’d change)

1. We added too many emails too fast

In month 6, we added a “tips & tricks” automation that fired every other day. Unsubscribe rate jumped from 0.8% to 1.6% in 2 weeks. We pulled it back to weekly and unsubscribe rate returned to normal.

Lesson: More emails ≠ more revenue. There’s a real saturation point.

2. We didn’t A/B test subject lines from the start

MailerLite’s subject line A/B testing is built in. We used it starting month 7. Before that, we relied on gut feel. The tests consistently surprised us — the subject lines we thought would win lost by 20-40% open rate.

Lesson: A/B test every important send. Even if you think you know what works.

3. We waited too long to segment

The first 4 months, the platform sends the same emails to all subscribers. In month 5, we segmented by industry (agencies vs in-house teams) and saw a 28% lift in click-through for industry-specific content.

Lesson: Segment from day 1. It doesn’t need to be complex — even 2 segments (industry A vs B) drives measurable lift.

The cost breakdown

Item	Cost	Notes
MailerLite (12 months)	$390	Started free, ended at $50/mo
Email template design (one-time)	$0	We built them ourselves
Copywriting (ongoing)	$0	In-house
Total email cost	$390
Total email-attributed revenue	$50,170
Net ROI	$49,780	12,800% return

The takeaway

For B2B SaaS companies with under 5,000 subscribers, MailerLite is genuinely enough. You don’t need ActiveCampaign’s depth or HubSpot’s CRM. You need:

1. A solid welcome series (5 emails)
2. A behavior-triggered conversion automation (4 emails)
3. A weekly educational email
4. A re-engagement automation for dormant subscribers
5. A/B testing for subject lines

That’s it. The tool doesn’t matter as much as the strategy. But MailerLite’s $10/mo starting price makes it the obvious choice for most B2B SaaS companies under 5,000 subscribers.

If your list grows past 10,000 subscribers with complex automation needs, look at ActiveCampaign or Customer.io. For everything else, MailerLite handles it.

Frequently asked questions

Is this case study representative?

It’s a single case, but the patterns (behavior-triggered > time-triggered, single CTA per email, specific subject lines) are consistent with what we see across 30+ B2B SaaS clients. The 12,800% ROI is high because the starting point was $0 and the tool cost was minimal. Don’t expect the same percentage if you’re starting from a mature email program.

How long does it take to see results?

The first revenue from email typically appears in month 2-3 once the welcome series and trial-to-paid automations are optimized. Most of our clients see $1,000+/month in email-attributed revenue by month 4. Significant revenue ($5,000+/month) typically takes 6-9 months.

Can I replicate this with a different email tool?

Yes — the strategies work with any ESP. We chose MailerLite for this case because of the price-to-features ratio. ActiveCampaign or ConvertKit would also work, but the cost would be 3-5x higher for similar results at the same list size.

What’s the single most important automation?

The trial-to-paid series. If you only have time to build one automation, build this one. It directly drives revenue and the conversion lift is measurable within 2 weeks.

Quick pros and cons

What we like

• Free tier covered our first 3 months (under 1,000 subscribers)
• Automation builder is genuinely enough for 90% of B2B SaaS needs
• Landing page builder saved us $80/mo on a separate tool
• Deliverability best-in-class
• Customer support is email-only but responds in 4-12 hours

What we don't

• Reporting depth is shallower than HubSpot or ActiveCampaign
• We outgrew some advanced conditional splits after 8,000+ subscribers
• No built-in CRM meant we had to integrate with HubSpot Free for sales
• Subject line A/B testing only (no content or send-time testing)

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