Opportunities › Email relay for self-hosted applications › Proposed app
Slipway
Mail gateway for self-hosted apps that sends past blocked SMTP ports
- Score
- 69
- confidence 53
- Evidence
- 12
- items on the page
- Rivals
- 6
- named in sources
- First version
- 25 d
- estimate
- Type
- Desktop app
- PWA: runs in the browser, installs on Mac and Windows
- Market since
- 2010
- Mature market · AI estimate
ScreensConcept
Desktop app: Developers and admins configure mail routing, review delivery logs, and troubleshoot failures at a desk with keyboard work and dense monitoring dashboards. Sample screens on a computer, in the proposed brand. Their numbers are sample data.
Today
All providers healthy214 sent
About this appAI proposal
Slipway is a small mail gateway you run next to Ghost, Gitea, Mastodon or a static site. Your apps talk to it like an ordinary SMTP server or a form endpoint. It forwards the mail over HTTPS to the transactional provider you already use, so blocked SMTP ports stop mattering.
It is for developers and sysadmins on small VPS plans, and for creators whose static sites have contact forms. One config file replaces a hand-built Postfix relay and a form service that keeps spam filtering behind a paid plan.
Anti-spam, rate limits and honeypot fields are part of the gateway, not a paid add-on. A hosted option exists for people who would rather not run it themselves.
- Tagline
- Your self-hosted apps' mail, launched past the blocked port.
- Voice
- PlainPracticalCalm
- Why this name
- A slipway is the ramp that launches a boat into water. Slipway launches your app's mail past a blocked port. Short, easy to say, and not tied to any email product.
In the first version
Members say which features they would use. It tells PWAS what people want; it changes no score.
SMTP in, HTTPS out
Apps send to a local SMTP port. Slipway relays through a provider's HTTPS API, so blocked ports 25 and 587 no longer stop delivery.
No member yet
Bring your own provider
Connect Amazon SES, Mailgun, Postmark or Resend. Set a primary and a fallback so one provider outage doesn't lose mail.
No member yet
Form endpoints for static sites
Give each contact form a URL. Submissions are checked, then emailed to you. No separate form service or free-tier cap.
No member yet
Spam defenses included
Honeypot fields, per-sender rate limits, allowed-origin lists and content rules are on by default in every plan.
No member yet
Brand identityAI proposal
Check the name against trademark registers before using it.
Palette
#1F6F5CHarbor Green · primary#F6F1E7Paper · surface#1F2A27Ink · text#E0822BBuoy Orange · accent#3A5F8FTide Blue · data
Typography
Aa
Slipway
ABCDEFGHIJKLMNOPQRSTUVWXYZ 0123456789
Your self-hosted apps' mail, launched past the blocked port.
PricingAI proposal
Verified competitor prices: Postmark $5 to $50, Formspree and Mailgun $15 to $90, Resend $20 to $150 a month. Slipway tiers sit at the low end as a starting point to test; mail provider costs are billed by the provider.
Self-hosted
Free
- Run it on your own server
- All spam defenses
- Unlimited apps and forms
- Your own provider keys
Hosted
$5 a month
- We run the gateway for you
- Up to 5 apps or forms
- 30-day delivery log
- Email failure alerts
Hosted Plus
$15 a month
- Unlimited apps and forms
- Provider fallback
- 90-day delivery log
What it could be worthEstimate
What a software business making this much sells for today, from real deals. Pick a monthly revenue.
If it makes
Worth about
$190,000
Sale range $132,000 to $263,000
$120,000 a year in revenue
From 87 software businesses listed and sold on Empire Flippers in the last year, revenue vetted by the broker: they sell for about 19× their monthly revenue, most between 13× and 26×.
Measured on profit, the middle deal is 32× monthly net profit: about 2.7 years of profit.
An estimate, not an offer or financial advice. A real price depends on profit, growth, churn, how much of the work is the owner's, and the buyer.
How it would growAI proposal
How the product would reach new customers through its own use, and how the first ones would be found. A plan to test, not a result.
- Built-in loop
- No loop in the product. Slipway runs behind the scenes of apps and forms, so its own use does not show the name to others. Growth comes from setup guides, app-specific presets, community answers and search.
- Do they become customers?
- Developers who find a guide can become paying hosted users. Test whether self-hosters who start free convert to the hosted tier.
- First customers
- Solo developers and small teams self-hosting Ghost or Gitea on a small VPS, plus creators with a static site and a contact form.
- Where to reach them
- Hacker News and Reddit: Share a write-up of the SMTP block problem and open-source the gateway; answer threads where people ask for relay workarounds.
- Setup guides: Publish step-by-step guides for Ghost, Gitea, Mastodon and static contact forms that search engines can find.
- App communities: Offer presets in the forums and chats for self-hosted apps like Umami and Comentario.
- First milestone
- Fifty self-hosted installs and ten paying hosted users within 60 days of launch.
Why people already pay for this
- VerifiedHacker News post received 83 points and 60 comments
- Public claimVPS providers block default SMTP ports to combat abuse, making email delivery difficult for self-hosted applications
- Public claimThe SMTP port blocking issue affects multiple categories of self-hosted applications
- Public claimFree email form services like Formspree have usage limits and anti-spam features gated behind paid accounts
- Public claim
Tech stack
Every proposal builds on the same PWA base, installable from the browser on any phone or computer. Dashed boxes are what this app adds.
- AppNext.js and TypeScript
- PWAManifest and service worker
- UITailwind CSS
- Data and authSupabase Postgres
- PaymentsStripe
- EmailResend
- HostingVercel
- This app · Gateway serviceSmall SMTP and HTTP server in a containerThe self-hosted gateway must accept SMTP and form posts, which the web stack alone does not do.
- This app · Job queuePostgres-backed retry queueMessages need durable retries and backoff when providers fail.
RisksAI inference
- CommercialA free self-hosted tier may satisfy most users, leaving few to pay for hosting. Willingness to pay for the hosted version is untested.
- TechnicalSMTP edge cases (attachments, encodings, odd client behavior) across Ghost, Gitea and Mastodon may cause subtle delivery bugs.
- PlatformProviders may restrict relaying on behalf of others or suspend accounts if a Slipway user sends spam through shared keys.
- RegulatoryHosted mode handles message contents and personal addresses, which brings privacy duties and abuse-handling obligations.
- CommercialUsers can add a relay with an existing tool such as Postfix, so Slipway must be clearly quicker to set up.
Everything marked AI proposal or AI inference was written by a model from the evidence on the opportunity page. The proposed name must be checked against trademark registers before it is used.