SMTP-365 is a small relay that runs on your network. Printers and other legacy devices keep sending plain SMTP exactly as they always have; SMTP-365 delivers it to Microsoft 365 securely with modern authentication, and can file scans straight into SharePoint.
One appliance covers every device on your network: all your printers, UPSs, servers, NAS and phone systems, on one licence with 12 months of updates included. No per-user or per-device fees.
Multi-function printers only speak legacy SMTP, usually with no authentication and often no TLS. Exchange Online now refuses that, so scan-to-email quietly stops working.
UPS units, server management cards, NAS boxes and phone systems all email their warnings the same way. When they can't, you don't find out until something has already failed.
Turning security settings back on, exposing SMTP relays, or hand-building OAuth2 connectors per device: fragile, risky, and a job nobody wants to own.
Change the SMTP server on your printer or device to the relay's address. No username, no password, no certificates. That's the only change your devices ever need.
Every message is written to disk, then sent to Microsoft 365 using an application identity that holds only Mail.Send, Sites.Selected and, for large attachments, Mail.ReadWrite. Temporary Microsoft outages are retried automatically.
Messages are sent from a mailbox you choose. Scans addressed to name@sharepoint.local are converted to PDF and filed in the SharePoint folder you mapped in the browser.
The email relay path serves every legacy SMTP source. Scan-to-SharePoint is the document-centric extra that makes it shine on multi-function printers.
Scan to email, or straight into a SharePoint folder as a PDF. Any brand that can send SMTP.
APC, Eaton and others: power, battery and self-test alerts keep arriving.
HP iLO, Dell iDRAC, Lenovo XClarity hardware and health notifications.
Synology, QNAP and others: backup, disk and job reports.
PBX and VoIP voicemail-to-email and system alerts.
Access control, alarm panels and building-management notifications.
Any tool or line-of-business application that emails reports over SMTP.
Send everything from one fixed, trusted address, so alerts from a UPS or iLO still land properly.
Map addresses to folders with a live folder picker. TIFF, JPEG and PNG scans become one multi-page PDF; PDFs pass straight through.
Every message is spooled before the device is told "accepted". Retries with back-off, held scans for unmapped addresses, and alert emails to the admin on failure.
Sign in once as a Global Administrator; the appliance registers its own app with the permissions it needs (three at most) and access to one SharePoint site. No PowerShell is needed to connect; one recommended Exchange PowerShell step afterwards limits the app to your scanner mailbox, and the appliance then checks that the limit is in force. Verified publisher: Interop Solutions Ltd.
Mail.Send, Sites.Selected on one site, and, only if you tick large attachments, Mail.ReadWrite, which Microsoft requires for email attachments over 3 MB. The mail permissions cover every mailbox in your tenant until you apply the Exchange scope the setup page gives you; applying it is recommended and limits the app to your scanner mailbox. The appliance checks the scope for you and says so on every page until it is confirmed.
HTTPS admin UI, firewall managed in the browser, backup and restore, logs, and one-click signed software updates.
Runs on your premises. Your documents go from your printer to your tenant and nowhere else. Licences are verified offline; the product keeps working without us.
Ready-made images for VMware, Hyper-V, Proxmox/KVM, plus a bootable installer ISO for any hypervisor or bare metal.
A signed package for your existing Debian or Ubuntu server, updated through apt.
A flashable image for Pi 4 and Pi 5 for small sites that want a tiny always-on box.
An MSI that installs SMTP-365 as Windows Services on an existing server.
One licence covers one installation of any edition.
Founder price for the first 100 customers · limited remaining. Renewals are £39 a year for everyone, and never required to keep working.
One appliance or installation, any edition. Perpetual licence.
Prices in GBP. VAT may apply. Your key is emailed within minutes of payment.
15 percent off for 5 or more appliances, 25 percent for 20 or more; education and registered charities 30 percent off. Ask for a quote.
Resell it to your clients at partner prices. See the partner programme.
The relay keeps working indefinitely. Renew maintenance for £39 per appliance per year to keep receiving updates, new versions and support. No renewal, no problem: nothing stops.
£5 per appliance per month, same product, cancel any time. Subscribe monthly. A subscription key is not a perpetual licence: cancelling the subscription, or a full refund, revokes the key, and an appliance with internet access then holds scans (it does not lose them) until a valid key is entered.
Payments are taken by Paddle, our merchant of record. Your key arrives by email within minutes. Refund policy.
Sales and general enquiries: hello@smtp-365.com
Technical support: helpdesk@smtp-365.com
Step-by-step settings for the printers we see most, plus what Microsoft changed and how the alternatives compare.
The errors you will see, what each one means, and the fix.
Server, port and auth for every method, and which ones still work for devices.
Basic auth retired, Direct Send locked down, and your options now.
One address per folder, from any printer, no vendor app.
Printer setup: Canon · Ricoh · Konica Minolta · Xerox · HP · Kyocera · Brother | Other devices: UPS · iDRAC and iLO · Synology and QNAP · 3CX | All guides
It runs entirely on your premises. Scans and alerts travel from your device to your Microsoft 365 tenant through the appliance and nowhere else. Interop Solutions never receives your mail. The only thing the appliance sends us is licence data: when you enter a licence key, each time the relay service starts and once a day, it sends the licence key, its appliance id, its hostname and the product version to our licence server, and an update check when you ask for one. An appliance with no internet access keeps working on its key.
A Global Administrator to sign in once during setup, a mailbox to send from (a free shared mailbox is fine), and a SharePoint site if you want scan-to-SharePoint. The setup wizard creates the app registration for you with up to three application permissions: Mail.Send, Sites.Selected and, only if you tick large attachments, Mail.ReadWrite (Microsoft requires it for email attachments over 3 MB). The mail permissions cover every mailbox in the tenant until you apply the Exchange scope that the Microsoft 365 page gives you; applying it is recommended, and the appliance can then check that it is in force.
Anything that can send email over SMTP to a server address you choose, with authentication and TLS turned off: printers, UPS units, iLO/iDRAC/XClarity, NAS, PBX and VoIP systems, alarms, monitoring tools and applications.
Today as a virtual appliance on VMware, Hyper-V, Proxmox/KVM or from a bootable ISO on any hardware. It needs about 1 vCPU, 2 GB RAM and a LAN address the devices can reach, plus outbound HTTPS to Microsoft (login.microsoftonline.com and graph.microsoft.com) and to licence.smtp-365.com for licence checks and updates. Linux package, Raspberry Pi and Windows Server editions are on the roadmap.
Messages are spooled to disk and retried with exponential back-off for about half an hour (2, 4, 8 and 16 minutes), then kept for you to re-queue with one click (for 30 days by default; you choose how long). A Microsoft sign-in outage only delays scans.
In one way only. The 30-day evaluation delivers mail exactly as a licensed appliance does, but an evaluation appliance cannot install update bundles that are tied to a maintenance date, which most are: enter a licence key to update, or download the current image. When the evaluation ends, scans are held rather than lost until a licence key is entered.