Download SMTPly
14 days of full functionality, no restrictions. After that, relay operation pauses until you activate a license — your configuration and logs are preserved.
SMTPly — Windows installer (x64, latest version)
Launch once, walk through the setup wizard, enter your Azure app registration, done. The installer optionally registers the Windows service "Smtply" with automatic start.
SHA-256: 11982fe3abafa7cf1de4b40223a257a8c73b166bf46e4eb2b50bbda46fbf274f
Windows note: When downloading or launching the installer, Windows Defender / SmartScreen may flag it as "untrusted" or "not commonly downloaded". This is normal for any brand-new release until enough users have downloaded the same file — SmartScreen reputation builds up automatically over time.
How to run the installer anyway:
- In the browser download: click "Keep" → "Keep anyway".
- On "Windows protected your PC": click "More info" → "Run anyway".
- Before running, verify the SHA-256 against the hash shown above (PowerShell:
Get-FileHash SMTPly-Setup-latest.exe) — that's the most reliable trust check.
Why no signature yet? Code-signing certificates are a noticeable recurring cost for a small solo vendor. While the user base stays compact we rely on SHA-256 verification against the hashes published here. An OV code-signing certificate is on the roadmap and will be added as soon as it's economically reasonable — the SmartScreen warning fades out from there.
System requirements
- Windows 10 / 11 or Windows Server 2016 / 2019 / 2022 / 2025 (x64)
- Administrator rights for initial install and service registration
- A Microsoft 365 tenant with global admin rights for app registration
- Port 25 or 587 available on the bind address
Ready in 5 steps
Run the installer
Run as administrator. Setup places SMTPly under Program Files\SMTPly\ and optionally registers the service.
Register the Azure app
Create an app registration with the Mail.Send application permission in the Entra admin center. The setup wizard shows the exact steps. Guide →
Enter credentials
Enter tenant ID, client ID, client secret and sender address in the GUI. Everything is stored DPAPI-encrypted locally.
Reconfigure the device
On the printer, ERP system or third-party application, set the SMTP server to your Windows server's IP and the configured port. No auth required — SMTPly handles OAuth2 in the background.
Send a test mail
The first mail appears in the mail tracker within seconds. If not, the system log provides a plain-text error message.
What's in the download?
- Smtply.Service.exe — Windows service (worker) with SMTP listener and Graph relay
- Smtply.exe — WPF configuration GUI with dashboard, log viewer and setup wizard
- Self-contained .NET 8 runtime — no separate install needed
- All required libraries — MSAL, Graph SDK, SmtpServer, Serilog, SQLite
Activate your license
After purchase you'll receive a license key by email (format: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX). In the GUI, open the "License" navigation item, paste the key and click "Activate". The license is then bound to the server hardware.
For server migration, first click "Deactivate (release license)" in the GUI — then the same key can be activated on the new server.
No license yet? No problem. After download SMTPly runs 14 days fully functional as a trial. You can purchase and activate a license at any time — even during the trial, to replace the trial counter immediately.
Ready for production?
Starter from €149, Business €249 — one-time purchase, 1 license per server, unlimited mail volume. Compare editions →