What you’re seeing
- Scan-to-email works for internal addresses, but scans to customers or personal addresses fail with '550 5.7.1 Unable to relay'.
- A line-of-business application or web form logs relay-denied errors when emailing outside recipients.
- The device shows a generic send failure, and the mail server logs show the connection being rejected.
- It worked before a server migration, firewall change or switch to Microsoft 365.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- The device sends without signing in, and the mail server only lets anonymous senders deliver to internal mailboxes.
- The relay connector that permits the device's IP address is missing, or the device's IP address has changed.
- Mail is now handled by Microsoft 365, and the old on-premises relay settings no longer apply.
- The device is sending to the wrong server or port, landing on a connector meant for inbound internet mail.
- The sender address the device uses is not a recognized address for your domain.
Why it matters
Copiers and business applications often send invoices, statements, reports and scanned documents directly to customers. When outside delivery fails, that paperwork silently stops leaving the building, and staff fall back on saving scans and attaching them by hand. Fixing it hastily by opening the server to relay anyone is dangerous: an open relay can be abused by spammers within hours, leading to blocklisting of your whole domain.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Why does it work for internal addresses but not external ones?
Delivering to your own mailboxes is ordinary inbound mail, which any server accepts. Sending onward to the outside world is relaying, which mail servers only permit for trusted, authenticated senders.
Can you fix it without making our server less secure?
Yes. The goal is to trust only the specific device or application, never the whole internet, and we confirm how the device sends before changing anything.