HP printer: “SMTP server requires authentication”
The message means the mail server refused the printer’s login. It is not a fault in the printer, and replacing it will not fix anything.
There are three reasons an HP printer sees it, and they need different answers.
1. No credentials were entered
The outgoing email profile has a server and a port but no username and password, or “server requires authentication” is unticked. Most mail servers stopped accepting anonymous mail years ago, so the printer connects, offers no identity, and is turned away.
Fix it in the profile: Embedded Web Server (a browser pointed at the printer’s IP) → Networking or Scan → TCP/IP Settings → Outgoing Email / Scan to Email → Outgoing Email Profiles. The printer’s IP is on the panel under Settings → Networking → TCP/IP Settings.
2. The credentials are right and the server refuses them anyway
This is the one that is growing, and it is not a mistake anybody made.
Microsoft is switching off Basic authentication — username and password — for SMTP AUTH in Exchange Online at the end of December 2026. A printer that has worked for years starts being refused on a day nobody touched it. The password is still correct; the method is no longer accepted.
Confirm which case you are in from a laptop on the same network:
npx zerosmtp-check --explain "535 5.7.139 Authentication unsuccessful"
Nothing is installed and no mail is sent. Every SMTP AUTH error and what it means covers seventeen of these strings, and says for each whether the cause can still be turned back on before the deadline.
3. A consumer account that no longer allows it
Pointing an HP printer at Hotmail, Outlook.com or Gmail with the account password stopped working some time ago; those providers now require OAuth or an app password, and most printers can offer neither. If that is the setup, this is the cause and no amount of retyping the password will change it.
Can an HP printer do OAuth instead?
Sometimes, and the answer depends on the exact model rather than on HP as a brand.
HP documents OAuth 2.0 for Microsoft 365 Scan to Email on HP Enterprise and HP Managed printers running FutureSmart firmware 5.7 or newer. HP also states that certain LaserJet Pro models — the M478-M479 and M428-M429f among them — do not support OAuth 2.0 at all.
That second half is the part worth reading twice. On those models there is no firmware coming that will fix this, so waiting is not a plan. Check your exact product family against HP’s own statement, and the full compatibility list for every other vendor.
If the model cannot do OAuth
The printer needs a mail server that still accepts a username and password. That is what ZeroSMTP is for:
| Setting | Value |
|---|---|
| Server | mx.msgwing.com |
| Port | 587 (STARTTLS) or 465 (SSL/TLS) |
| Authentication | On, with the username and password from registration |
Mail sent this way leaves from a generated @msgwing.com address rather than your own domain, and the cap is 200 messages a day with no paid tier that lifts it. For scan-to-email from a printer that is usually the right trade; if the From address has to be your own domain, the alternatives page says which tool is.
Still refused after changing the server?
Then the printer is not reaching the server at all, which looks identical from the panel. Check the network path from a machine on the same subnet:
npx zerosmtp-check
It tests ports 25, 587 and 465 and reports which of them the network actually lets out — a firewall blocking outbound 587 produces the same silence as a wrong password. Troubleshooting covers the rest.
Related
- Scan-to-email setup for every brand
- Which devices have OAuth firmware
- Devices whose vendor has ruled OAuth out
Updated 23 Aug 2026