EmailEngine
Self-hosted email API that turns IMAP and SMTP into REST
TL;DR: Self-hosted email API that turns IMAP and SMTP into REST. Reached ~$6,600 MRR with 150+ companies users.
Key Metrics
As of 2024-02
Milestones
Pricing
Tech Stack
Sources
Timeline
2009
Andris Reinman begins publishing open source software with MIT/BSD licenses, including early email libraries
2010
Nodemailer first published for Node.js, enabling developers to send emails programmatically
2012
Worked at CRM startup (email integration role), identified persistent challenge of integrating services with customer mailboxes
2015
Nodemailer gains widespread adoption, used by reputed companies. Andris prioritizes reach over monetization
2018
Startup using Nodemailer acquired for [unverified amount]. Andris receives zero compensation despite library handling millions of daily emails. Searched correspondence and found only one complaint, no donations or PRs from the company
2020-02
Created IMAP API (predecessor to EmailEngine) - open source IMAP library built from scratch for email debugging app. GitHub repo created Feb 28, 2020
2020-03
Published IMAP API under LGPL copyleft license. Offered MIT version for paying subscribers at 250 EUR/year. Required CLA from all outside contributors from day one
2020-08
Show HN: IMAP API - Self-hosted access to IMAP over REST posted on Hacker News
2020-12
After ~9 months of LGPL model, only 3 subscribers. Total revenue: ~750 EUR. Smaller companies ignored license, larger companies did not use it
2021-05
Raised price of IMAP API subscription to 495 EUR/year for new subscribers
2021-08
Show HN: EmailEngine, open source REST interface to read and send email messages (rebranded from IMAP API)
2021-11
EmailEngine v2 launched with complete rewrite. Major pivot: switched from AGPL to commercial license with mandatory license key. App stops working 15 min after startup without valid key. UI redesigned for professional appearance
2021-11
First week after commercial pivot generated more revenue than entire previous 18 months. Month 1 revenue: 1,750 EUR vs 750 EUR total from 1.5 years of free model
2021-12
Launched on Product Hunt, reached #2 Product of the Day with 177 upvotes. Minimal direct customer conversion but credibility boost
2022-01
Continued price increase to 695 EUR/year for new subscribers. Existing customers grandfathered at original price
2022-05
Price increased to 795 EUR/year. Growth steady with no reduction in customer acquisition from price increases
2022-07
Reached $1,000 MRR milestone. First 4-figure monthly recurring revenue
2022-10
Reached $20K ARR at beginning of October 2022
2022-11
Reached $2,000 MRR with 59 paying subscribers. Maintained 10%+ month-over-month growth for consecutive months
2022-12
Full year 2022 revenue: 36K EUR ($40K). Established yearly subscription-only model for accounting simplicity
2023-01
Price increased to 895 EUR/year. Sub-1K amounts for businesses validated as trivial budget items
2023-06
Subscriber count up 70% from 2022. Annual churn at 20%, consistent with prior year
2023-06
Attempted enterprise sales as solopreneur. Six months of negotiations with three prospects yielded zero conversions
2023-09
Discovered that offering discounts was counterproductive - discount-requesting customers churned regardless
2023-11
Graduated from micro-business to small-business under Estonian accounting regulations. Implemented Stripe Tax for sales tax compliance
2023-12
Full year 2023 revenue: 73K EUR ($80K). ARR reached 65K EUR. MRR, ARR, and net cash flow all grew 100%+ vs 2022. Set 100K EUR ARR target for 2024
2024-02
Published detailed blog post about turning open source into a business. MRR at 6,100 EUR (~$12K MRR equivalent), enabling full-time work from Estonia
2024-06
EmailEngine reaches 12K USD MRR. Trusted by 150+ companies across CRM, SaaS, and AI sectors
2025
Price increased to $995/year. Added Gmail API and Microsoft Graph API support alongside IMAP/SMTP. Custom enterprise licensing available
2026-02
EmailEngine v2.62.2 released. Total of 284 releases. GitHub: 2.1K stars, 207 forks, 19 contributors
Distribution
Open Source Ecosystem
Nodemailer (7M+ weekly npm downloads) documentation pages link to EmailEngine. ImapFlow library also drives referral traffic. Combined, open source projects drive ~66% of EmailEngine's homepage traffic.
→ 6,000 unique monthly visitors, 100K+ annual organic visitors, zero marketing spend
SEO
Blog posts targeting email protocol topics, IMAP integration guides, and technical content that EmailEngine's ICP (CTOs at SaaS companies) actively searches for.
→ ~34% of traffic from organic search, sustained channel requiring no ongoing spend
Hacker News
Guerrilla blog post submissions about email topics. Multiple Show HN posts for IMAP API (2020) and EmailEngine (2021).
→ Developer awareness and credibility, complementary traffic spikes
Product Hunt
Launched in December 2021, reached #2 Product of the Day with 177 upvotes.
→ Credibility badge and SEO backlinks but minimal direct customer conversion
Launches
Show HN: IMAP API (predecessor) - developer awareness
Show HN: EmailEngine - rebranded launch
#2 Product of the Day, 177 upvotes, minimal direct conversion
Growth Story
Andris Reinman spent 15+ years building free open source email tools (most notably Nodemailer with 7M+ weekly npm downloads) before commercializing his expertise as EmailEngine. The original product launched as IMAP API under AGPL in 2020 but earned only 750 EUR in 18 months with 3 subscribers. The breakthrough came in November 2021 when he rebranded to EmailEngine, switched to a commercial license with mandatory license keys, and redesigned the UI. Free users converted within one week, generating 7x the previous 18 months of revenue. Progressive price increases from 250 to 895 EUR/year never reduced customer acquisition. By 2024, the one-person operation reached $12K MRR with 150+ company customers and zero marketing spend.
Key Insights
- →Open source reputation is valuable as a distribution channel but worthless as a revenue model - Nodemailer users included companies acquired for $500M while Andris received zero compensation
- →The licensing pivot from AGPL to commercial source-available generated more revenue in 2 weeks than 18 months of the free model, proving users valued the product but would not pay voluntarily
- →Progressive price increases from 250 to 895 EUR/year did not reduce customer acquisition, validating that sub-1K annual fees are trivial for business customers
- →Identifying the ICP as CTOs at small SaaS companies who understood email integration complexity transformed messaging and correlated with the beginning of real traction
- →Requiring CLAs from day one enabled the entire commercial pivot - without it, relicensing would have been legally impossible due to external code contributions
- →Open source projects (Nodemailer, ImapFlow) serve as permanent traffic funnels driving 66% of EmailEngine's 6K monthly visitors with zero marketing spend
- →Enterprise sales attempts as a solopreneur failed completely - six months of negotiation with three prospects yielded zero conversions, validating the self-serve SMB model
- →Offering discounts proved counterproductive as discount-seeking customers churned regardless, reinforcing full-price positioning
- →Self-hosting as product architecture eliminates operational overhead for the vendor while giving customers data sovereignty - a key differentiator against cloud-based competitors like Nylas
- →Flat annual pricing with unlimited mailboxes creates a simple, predictable cost structure that becomes increasingly cost-effective for customers as they scale
Challenges
- !Spent 15 years building open source for free before realizing the business model was broken - biggest regret was not monetizing sooner
- !Enterprise sales as a solo founder proved impossible: six months of negotiations with three prospects yielded zero conversions
- !Transitioning from micro-business to small-business tax status required implementing Stripe Tax for sales tax compliance across regions
- !Overpromising features to prospects who signed based on planned capabilities, then lacking capacity to deliver while managing all operations solo
- !Linear growth with decreasing percentage gains despite increasing absolute numbers meant scaling required patience rather than hockey-stick expectations
Target Audience
CTOs and developers at small SaaS companies who need email integration without building IMAP/SMTP from scratch. Also serves web agencies, email hosting providers, cold outreach services, and AI companies needing programmatic email access.
Problem Solved
Building email integrations from scratch requires deep knowledge of IMAP, SMTP, obscure encodings, and protocol-level debugging. Cloud-based alternatives like Nylas charge per-mailbox fees that scale poorly and require sending credentials to third parties. EmailEngine solves both by providing a simple REST API that runs on your own infrastructure with unlimited mailboxes for a flat fee.