Connect any device to reliable email delivery

Getting started

DeviceSMTP is a specialist SMTP gateway for physical devices — printers, IP cameras, alarm panels, HVAC controllers, PLCs, sensors and other hardware that needs to send email. Instead of pointing a device at a general-purpose mailbox provider that may block it or drop legacy logins, you point it at DeviceSMTP, which accepts the message over standard SMTP and relays it reliably to the recipient.

Nothing is installed on the device and no code is required. You change only the SMTP settings the device already exposes: host, port, encryption, username, password and the “from” address.

To connect your first device:

• Create a DeviceSMTP account and sign in to your dashboard.
• Create a set of SMTP credentials — ideally one per device so each can be rotated or revoked on its own.
• Open your device’s email or SMTP settings screen and enter the host, port, encryption, username and password shown in your account.
• Set a sender (“from”) address on a domain you control and send a test message.
• Confirm the message in your email activity log.

SMTP configuration

Every device that sends email over SMTP needs the same handful of settings. Enter these in your device’s email or notification configuration screen:

SMTP ports

DeviceSMTP accepts connections on several submission ports so you can match whatever your hardware supports. Choose the first one your device can use:

Which to pick:

• Start with 587 if the device supports STARTTLS — it is the standard submission port.
• Use 465 if the device only offers an “SSL/TLS” option with no STARTTLS toggle.
• Fall back to 2525 if connections on 587 and 465 time out or are refused on your network.

TLS & SSL

DeviceSMTP requires an encrypted connection before your device authenticates, so your credentials and messages are never sent in the clear. There are two ways to establish that encryption, and your device will offer one or both:

• STARTTLS (ports 587 / 2525): the session opens in plain text, the device issues the STARTTLS command, and the connection upgrades to TLS before login. This is the modern default.
• Implicit TLS / SSL (port 465): the connection is encrypted from the very first byte, with no upgrade step. Choose this if your device labels the option simply as “SSL” or “TLS” with no STARTTLS setting.

The gateway negotiates modern protocol versions — TLS 1.2 and TLS 1.3 — with current cipher suites. The illustrative STARTTLS handshake below shows the upgrade step on port 587:

$ connect smtp.devicesmtp.com:587
220 DeviceSMTP ESMTP ready
EHLO camera-dock-3
250-STARTTLS
250 AUTH LOGIN PLAIN
STARTTLS
220 Ready to start TLS
# TLS 1.3 handshake — channel now encrypted ✓
EHLO camera-dock-3
250 AUTH available over secure channel

Authentication

DeviceSMTP uses standard SMTP authentication: the device logs in with a username and password using AUTH LOGIN or AUTH PLAIN. Authentication is only offered over an encrypted channel, so credentials are never transmitted in plain text.

• Per-device credentials: issue a separate SMTP username and password for each device. Label them meaningfully (for example “Camera — Warehouse entrance”) so your activity log reads like your building.
• Rotation: change a device’s password at any time from the dashboard, then update that one device — the others keep working.
• Revocation: if a device is retired or compromised, revoke just its credentials without affecting the rest of your fleet.

Sender domain

The “from” address your devices use should be on a domain you control. Verifying that domain and aligning its authentication records helps receiving mail servers trust messages relayed on your behalf, so device mail lands in the inbox rather than the spam folder.

Two mechanisms do most of the work:

• SPF lets you publish which servers are allowed to send mail for your domain, so a receiver can check that DeviceSMTP is an authorized sender.
• DKIM adds a cryptographic signature to each message so a receiver can confirm it was not altered and genuinely came from your domain.

The exact records to publish are generated for your domain inside your account. The snippets below are illustrative examples only to show their general shape — do not copy these values; use the ones shown in your dashboard:

# SPF (TXT on your domain) — example
yourcompany.com. TXT "v=spf1 include:_spf.example-provider.com ~all"
# DKIM (TXT on a selector) — example
selector._domainkey.yourcompany.com. TXT "v=DKIM1; k=rsa; p=<public-key>"

Printer setup

Most network printers and multifunction devices can email scanned documents or send status alerts over SMTP. The exact menu names vary by manufacturer, but the path is always the same. From the printer’s web interface or front panel:

• Open Settings → Network → Email (sometimes “Scan to Email” or “SMTP Server”).
• Set the SMTP server / host to your gateway hostname from your account.
• Set the port and encryption — 587 with STARTTLS where supported, otherwise 465 with SSL/TLS.
• Enable SMTP authentication and enter the username and password for this printer’s credentials.
• Set the from address to a sender on your verified domain.
• Save, then use the printer’s “send test email” button and confirm the message in your activity log.

Camera setup

IP cameras and NVRs typically send an email when an event occurs — motion detected, a tripwire crossed, or storage running low. Configuring that email uses the same SMTP settings. From the camera or NVR interface:

• Open Configuration → Network → Email (or “SMTP” / “Email on event”).
• Set the SMTP server to your gateway hostname, with the port and encryption your model supports (587/STARTTLS or 465/SSL).
• Enable authentication and enter this camera’s username and password.
• Set the sender address on your verified domain and add one or more recipient addresses.
• Choose which events trigger an email (motion, tamper, disk, etc.) and send a test.
• Trigger a real event and confirm both the email and the entry in your activity log.

Troubleshooting

Most device email problems fall into a few categories. Work through the symptom that matches, and check your activity log to see how far each message got:

Connection refused or timed out

The port is likely blocked on your network. Try port 2525, or switch between 587 and 465. Confirm the device has network access and the correct gateway hostname.

Authentication failed (535)

The per-device username or password is wrong. Re-enter the exact credentials for this device from your account — watch for trailing spaces — and make sure SMTP authentication is enabled on the device.

TLS / SSL handshake errors

The encryption mode is mismatched. Switch between STARTTLS (587/2525) and implicit SSL/TLS (465). On older firmware that negotiates obsolete TLS versions, update the firmware where possible.

Mail delivered but lands in spam

Verify your sending domain and align SPF and DKIM so receivers trust your device mail. Use a recognizable sender address on your own domain.

Message not received at all

Check your email activity log first. If the message is accepted but bounced, the log shows the receiving server’s reason. If there is no entry at all, the device never connected — revisit host, port and encryption.

Technical FAQ

Need help?

Can’t find what you need here? The general FAQ covers common questions, and you can always contact us with the specifics of your device and setup.