Canon MF657Cdw / MF655Cdw / MF651Cw: Scan to E-Mail Does Not Work — The E-Mail Is Not Sent

Last Updated on 14.04.2026 by DriverNew

Applies to models: Canon MF657Cdw, MF655Cdw, MF651Cw.

If the multifunction printer scans the document but does not send it by e-mail, this does not necessarily mean the device is faulty. In most cases, the issue is related to SMTP settings, authentication, the recipient address, TLS settings, or an incorrectly configured mail server on the machine.

How the problem usually appears

• the multifunction printer scans the document, but the e-mail is not sent;
• the control panel shows a send error message or an error code starting with #;
• scanning to a computer works, but scan to e-mail does not;
• the problem appeared after the initial mail setup or after the mailbox password was changed.

Why this happens

To send scans by e-mail, the machine must not only scan the document, but also connect correctly to the mail server. If [SMTP Server], [Use SMTP Authentication (SMTP AUTH)], the user name, the password, or the recipient address is incorrect, the e-mail will not be sent.

Canon also states that before you can send directly by e-mail, you must configure the e-mail server settings in advance. In other words, the fact that the machine can scan does not mean the e-mail sending function is already ready to use.

Where to start

1. Restart the multifunction printer.
2. If sending used to work before, think about whether the mailbox password or mail server settings were changed recently.
3. For the first test, use one or two simple pages instead of a large multi-page PDF.

If the e-mail still is not sent after that, move on to the settings.

Step 1. Make sure scan to e-mail is supported on these models and is meant to be configured

For the Canon MF657Cdw, MF655Cdw, and MF651Cw, sending scanned documents by e-mail is officially supported. In Canon documentation, this is described as sending scanned data directly from the machine as an e-mail attachment.

If scan to e-mail does not work, this is usually not about feature support. It is usually about correct setup.

Step 2. Check the basic e-mail settings through Remote UI

Canon recommends checking and changing the main e-mail settings through Remote UI.

1. Open a web browser on your computer.
2. Enter the IP address of the machine in the address bar.
3. Open Remote UI.
4. Log in in System Manager Mode.
5. Go to [Settings/Registration] → [TX Settings] → [E-Mail/I-Fax Settings].

This is where the main SMTP, POP, and TLS settings for this function are stored.

Step 3. Check [SMTP Server]

This is one of the most common causes of the error. Canon explicitly states that if e-mail cannot be sent because the SMTP or POP3 server settings are incorrect, you should check and correct [SMTP Server] and [POP Server].

1. In the SMTP settings area, find [SMTP Server].
2. Make sure the server name is entered without mistakes.
3. If your mail system uses a specific SMTP server, verify it in your mail provider’s documentation or with your network administrator.
4. After making corrections, save the settings and restart the machine.

Step 4. Check [Use SMTP Authentication (SMTP AUTH)]

Canon also states that if the server requires SMTP AUTH, you need to enable [Use SMTP Authentication (SMTP AUTH)] and specify the user name and password.

1. In the mail server settings, find the [Use SMTP Authentication (SMTP AUTH)] check box.
2. If your mail server requires authentication, enable it.
3. Enter [User Name].
4. Use [Set/Change Password] to set [Password].
5. Save the settings and try sending again.

If the mailbox password was changed recently, the old credentials stored on the machine will no longer work.

Step 5. If POP before SMTP is used, check that mode too

Canon also supports another authentication method: POP before SMTP. In the Canon English interface, this is called [Use POP Authentication Before Sending].

1. If your mail system uses this method, check whether [Use POP Authentication Before Sending] is enabled.
2. If you do not need this mode, do not enable it unnecessarily.
3. If you see POP or TLS related errors during sending, first verify whether this mode is configured correctly instead of changing unrelated settings at random.

Canon also notes that when there are POP-before-SMTP related issues, it may be necessary to disable [Use TLS for POP] or disable POP authentication before sending.

Step 6. Check the recipient address

For this product line, the recipient address itself is an important point. If the address is entered incorrectly, the e-mail will not be sent.

1. On the device panel, open the e-mail sending screen.
2. Check the recipient address if you enter it manually.
3. If the address is taken from the Address Book, open that entry through Remote UI and check the [E-Mail Address]/[I-Fax Address] field again.
4. For testing, try sending the document to another known-working address.

This is especially important if the error occurs only for one specific address while other addresses work normally.

Step 7. If the error appears only for one address, start with that recipient

If the problem occurs only with one recipient, first check that destination entry rather than the SMTP settings as a whole.

1. Delete the problematic address from the Address Book.
2. Enter it again manually.
3. If the e-mail is sent after that, the issue was in the destination entry rather than in the SMTP configuration.

Step 8. Check the TLS settings

Canon states that when SMTP and POP3 are used, TLS can be enabled for communication with the servers. But if the machine and the server do not share a compatible encryption algorithm, sending can also fail.

1. In Remote UI, open [Settings/Registration] → [TX Settings] → [E-Mail/I-Fax Settings].
2. Check [Use TLS for SMTP TX] and [Use TLS for POP].
3. If your mail system requires TLS, make sure the correct option is enabled.
4. If Canon shows an error about an incompatible encryption algorithm or certificate verification, test sending again after reviewing the TLS-related settings.

This step is especially important if the problem started after the security policy on the mail server was changed.

Step 9. If corporate mail is used, check whether the sign-in policy changed

Even if nothing was changed on the multifunction printer, the mail system itself may have changed its sign-in requirements. In practice, this means the old user name and password, or the old authentication method, may no longer work.

If you use corporate mail or a cloud mail service, you may need to verify the SMTP settings not only on the machine, but also with the mail administrator.

Step 10. If an error code appears in the log, use it for faster diagnosis

Canon publishes explanations for three-digit error codes that start with #.

• If the issue is related to the SMTP or POP3 server, first check [SMTP Server] and [POP Server].
• If the error is related to an incorrect user name or password, correct those values in [E-Mail/I-Fax Settings].
• If the error is related to TLS, check the SMTP/POP encryption settings and the server certificates.
• If #753 appears, Canon says to check whether the Ethernet cable is properly connected.
• If #755 appears, check the network status and settings, including the machine’s TCP/IP settings.

So the error code should not be ignored. It can significantly speed up the troubleshooting process.

Step 11. For the first test, send a small document

If you immediately try to send a large color PDF, that makes diagnosis harder. It is better to rule out basic setup problems first, and only then check attachment size and scan settings.

1. Use one or two sheets.
2. Select a normal PDF without extra options.
3. Try sending a test e-mail to a working address.

If that test works but a large document does not, then you can move on to checking attachment size and scan parameters separately.

How to quickly tell where the problem is

• If no e-mails are sent at all — first check [SMTP Server], [Use SMTP Authentication (SMTP AUTH)], and the machine’s network connection.
• If only one address does not work — first check that recipient or its Address Book entry.
• If the problem started after the password was changed — you almost certainly need to enter [User Name] and [Password] again.
• If the error appeared after mail security settings changed — check TLS and the authentication method.

When to contact support

• you have already checked [SMTP Server];
• you rechecked [Use SMTP Authentication (SMTP AUTH)];
• you checked the recipient address and the Address Book;
• you checked TLS and other security settings;
• you tested with a small document;
• the error still repeats.

If scan to e-mail still does not work after that, it is reasonable to contact Canon support or the administrator of your mail system.

Brief conclusion

For the Canon MF657Cdw, MF655Cdw, and MF651Cw, scan to e-mail problems are most often caused not by device failure, but by incorrect mail settings. First, check [SMTP Server], [Use SMTP Authentication (SMTP AUTH)], POP-before-SMTP settings, the recipient address, and the TLS settings. If no e-mails are sent at all, the problem is usually in SMTP or the account credentials. If only one address does not work, the most likely cause is the destination entry for that specific recipient.