The Quick Answer
HP M428fdw scan to email not working? A repair tech explains the SMTP authentication setting that breaks this feature most often, and 4 other fixes.
Scan to email is one of those features that works perfectly for months and then, seemingly overnight, just stops — no error you can point to, no obvious cause, just documents that scan fine but never arrive in anyone's inbox. If your HP LaserJet M428fdw's scan to email has stopped working, there's a good chance the actual cause isn't the printer at all, but a change on your email provider's side that broke a setting the printer depends on quietly, in the background, without telling you.
Quick-Fix Summary
Fast version:
- Confirm the printer's network connection is genuinely active.
- Recheck your outgoing (SMTP) server settings for accuracy.
- Verify email authentication — this is the fix that solves it most often. My uncommon tip.
- Check the recipient's spam folder before assuming nothing sent.
- Update the printer's firmware if authentication settings seem correct but still fail.
Fix 1: Confirm the Network Connection
Print a network configuration page from the M428fdw's control panel (usually under Setup or Reports) and confirm it shows an active IP address and successful connection status.
Why this works: scan to email requires the printer to actively reach out over your network to an outgoing mail server — if the printer's own network connection has dropped or changed, that entire chain breaks at the very first step, before authentication or email settings even come into play.
Fix 2: Recheck Your SMTP Server Settings
From the printer's control panel or its Embedded Web Server (accessible by typing the printer's IP address into a browser), navigate to the Scan to Email setup section and review your outgoing mail server (SMTP) settings — server address, port number, and encryption type (often SSL or TLS).
Why this works: these settings were entered once during initial setup and then largely forgotten, but email providers do occasionally change their required server addresses, ports, or encryption requirements over time, particularly as they tighten security standards. A setting that was correct when scan to email was first configured can quietly become outdated without any notification reaching you directly — the printer just starts failing silently instead.
Fix 3: Verify Email Authentication (My Uncommon Tip)
Here's the fix that resolves the most common version of this complaint, and it's almost always the actual root cause when scan to email was working fine for a long stretch and then suddenly stopped with no obvious explanation.
Major email providers — Gmail, Outlook/Microsoft 365, Yahoo, and others — have progressively tightened their security requirements over recent years, specifically around allowing basic username-and-password authentication from third-party devices like a scanner or printer. Many providers now require either an app-specific password (a separate, dedicated password generated specifically for a device like your printer, distinct from your normal account password) or have disabled basic authentication entirely in favor of more modern authentication methods that older printer firmware often can't use at all.
What this means practically: if your scan to email was configured using your regular email password, and it worked for a while before suddenly failing, your email provider very likely rolled out a security policy change that silently rejected the printer's login attempt going forward — the printer keeps trying to send with credentials that used to work and no longer do, often without displaying a clear, specific error explaining why.
To fix it: sign into your email account's security settings directly (search "[your email provider] app password" for exact steps, since the process varies by provider) and generate an app-specific password. Enter this new app password into the M428fdw's scan to email authentication settings in place of your regular account password.
Why this works: an app-specific password satisfies the provider's stricter security requirements — it's scoped narrowly to just this one purpose, can be revoked independently without affecting your main account password, and it's exactly the credential type most modern email providers now expect from a device like a printer rather than a full account login. This single change resolves the overwhelming majority of "scan to email suddenly stopped working" cases I encounter, because it addresses a security policy shift that happens on your email provider's end — something the printer had absolutely no way to warn you about in advance.
Fix 4: Check the Spam Folder Before Assuming Total Failure
Before concluding scan to email has failed completely, check the spam or junk folder of the recipient email address, including your own if you're testing by sending to yourself.
Why this works: automated emails from office equipment sending as an unfamiliar or generic address can occasionally get flagged by spam filters even when the sending process itself worked perfectly — this isn't the same problem as the authentication failures above, and confirming this possibility first prevents you from troubleshooting a "failure" that was actually a successful send landing somewhere unexpected.
Fix 5: Update the Printer's Firmware
If your authentication settings appear correct and current but scan to email still fails, check for and install the latest firmware for the M428fdw through the printer's Embedded Web Server or the HP Smart app.
Why this works: firmware updates occasionally include revised support for newer authentication standards and security protocols that major email providers have shifted toward, and a printer running old firmware may simply lack the technical capability to complete a login method your email provider now requires, regardless of how correctly you've entered your credentials.
When to Call a Professional
If the network connection is confirmed active, SMTP settings are current, you've set up and correctly entered an app-specific password, spam folders show nothing, and firmware is current — and scan to email still fails, the issue may involve firewall or network security settings blocking outgoing mail traffic on your specific network (particularly relevant in office environments with stricter IT policies), which is worth raising with whoever manages your network configuration. If you've confirmed it's not a network-blocking issue, contact HP support with your printer's serial number and firmware version, since a persistent failure despite correct settings on all sides points toward something worth their direct diagnostic attention.
FAQ
Why did scan to email suddenly stop working after months of no problems?
The most common cause is your email provider tightening its authentication security, no longer accepting your regular account password from a device like a printer. Setting up an app-specific password in the printer's email settings resolves this in most cases.
What is an app-specific password and how do I get one?
It's a separate password generated specifically for one device or application, distinct from your main account password, required by many email providers for third-party device logins. Generate one in your email account's security settings — search your specific provider's name plus "app password" for exact steps.
Could my company's network settings be blocking this instead?
Yes, particularly in office environments — outgoing mail traffic can be restricted by firewall or network security policy independent of anything wrong with your printer or email settings. If personal troubleshooting doesn't resolve it, this is worth checking with your network administrator.
Does the scan itself fail, or does the scan work but the email never arrives?
Usually the scan completes successfully and only the email sending step fails — check the printer's control panel for any error message specifically about the email send, and check spam folders before assuming complete failure.
HP LaserJet M428fdw scan to email not working almost always traces back to your email provider's authentication requirements changing quietly in the background, not a problem with the printer itself. Confirm your network connection and SMTP settings, but put real effort into setting up an app-specific password — it's the fix that resolves this exact complaint more often than everything else on this list combined.
Additional Resources
If you are still experiencing issues after trying the steps above, you may need to consult the official documentation or download the latest firmware for your specific printer model. We recommend checking the following official resources: