Xerox error 016-781 - SMTP server connection failed
The machine tried to send a scan by email and could not establish a connection to the mail server. Scanning itself worked; the delivery step failed. Incorrect server details, an authentication requirement or a blocked port are the usual causes.
What causes it
- The SMTP server address or port in the device is wrong
- The mail server requires authentication that is not configured on the device
- The mail provider requires TLS or an app-specific password the device is not using
- A firewall is blocking the outbound mail port
- The device's DNS settings cannot resolve the mail server name
How to fix it, in order
Work down the list and stop when the printer recovers. The steps are ordered from most likely and least invasive to last resort.
Open the Embedded Web Server
Type the printer's IP address into a browser to reach the device's web interface, then sign in as administrator. Scan-to-email settings are far easier to check and correct here than on the panel, and the page usually reports the last connection error.
Check the SMTP server address and port
Under the email or SMTP settings, confirm the server name and port match what your mail provider specifies, commonly port 587 with STARTTLS or port 465 with SSL. A port left at 25 when the provider requires 587 produces this exact failure.
Configure authentication
If the mail server requires a login, enable SMTP authentication on the device and enter the account username and password. Many providers no longer accept unauthenticated relay at all, which is a common reason a previously working configuration stops.
Use an app-specific password where required
Mail providers with multi-factor authentication generally require an app password rather than the account password for devices. Generate one in the mail account's security settings and enter that on the printer instead.
Check DNS on the device
In the network settings of the Embedded Web Server, confirm valid DNS server addresses are configured. If the device cannot resolve the mail server's name, entering the server's IP address directly is a quick way to confirm DNS is the problem.
Test with a simple internal address
Send a scan to an address on the same mail system as the sender account. Success there with failure to external addresses points at relay restrictions rather than at the device configuration.
Check firewall rules
Ask whoever manages the network whether outbound SMTP from the printer's IP is permitted. Many networks restrict mail ports to approved servers, and the printer needs an explicit allowance.
Stopping it happening again
When it is not worth fixing yourself
If you would rather not work through this alone, a printer specialist can take a look with you on a screen-share and tell you honestly whether the machine is worth saving.
Frequently asked questions
Which port should I use?
Most providers now use 587 with STARTTLS. Check your provider's documentation, as 25 is widely blocked.
Why did scan to email stop working suddenly?
Usually a password change, or the mail provider tightening its authentication requirements and no longer accepting the old method.
Can I use a personal email account?
You can, but an app-specific password is normally required and the account password changing will break scanning. A dedicated account is better.
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