scans to my computer are coming out huge, like 10MB per page, and they take forever to email

Diagnosis

The oversized files are caused by the printer's default "High Quality" scanning profile, which typically utilizes a 600 DPI (dots per inch) resolution and uncompressed TIFF or Full Color PDF formats. At 600 DPI, the scanner captures an immense amount of data per square inch; for a standard 8.5" x 11" page, this results in a massive bitmap that the printer then wraps in a PDF container without applying any compression algorithms. This is why a simple text document can balloon to 10MB or more. Furthermore, the MF453dw often defaults to "Full Color" mode even when scanning black-and-white documents. This forces the machine to process three color channels (RGB) instead of a single grayscale channel, tripling the data load. You can confirm this by checking the file properties on your PC; if the resolution is listed as 600 DPI and the format is "TIFF," you are capturing archival-grade images rather than office-grade documents, which is unnecessary for email transmission.

How to Fix It

To reduce file sizes for email and storage, you must modify the scan profile on the printer's control panel to prioritize "Compact" settings over "Quality" settings.

1. Place your document in the Automatic Document Feeder (ADF) or on the scanner glass.
2. On the home screen of the MF453dw, tap the Scan icon.
3. Select the destination (e.g., Computer or Email).
4. Tap the Settings button (represented by the wrench icon) on the right side of the screen.
5. Navigate to File Format. Change the selection from "TIFF" or "PDF" to PDF (Compact). This enables the internal compression engine to shrink the file size without noticeable quality loss.
6. Tap Color and change it from "Full Color" to Black & White or Grayscale, depending on the document content.
7. Tap Resolution. Change the setting from "600 x 600 dpi" to 200 x 200 dpi or 300 x 300 dpi. For standard text documents, 200 DPI is more than sufficient and will drastically reduce the MB per page.
8. Press OK to save these settings and then press the Start button to begin the scan.

If That Didn't Work

• Adjust the Remote UI Settings: Access the printer's web interface by typing the printer's IP address into a web browser. Navigate to Settings/Registration > Network Settings > Scan Settings. Ensure the default resolution is locked to 300 DPI globally so you don't have to change it manually every time.
• Update the MF Scan Utility: If you are scanning from the PC side using the Canon MF Scan Utility, open the software on your computer, go to Settings, and select the Custom Scan profile. Manually lower the resolution to 300 DPI and set the "Save as" format to "PDF (Compact)" within the software interface.
• Check for "High Quality" Presets: Some users accidentally select the "Photo" or "High Quality" preset on the home screen. Ensure you are using the "Document" preset, which is pre-configured for lower file sizes and faster transmission.
• Clear the Print Spooler/Memory: If the printer is lagging during the "Sending" phase, it may be due to a clogged memory buffer. Power cycle the machine by unplugging the power cord for 30 seconds to clear the temporary cache.

Heads Up

• Resolution Trade-off: Do not drop below 200 DPI for documents containing small text or fine lines, as this can cause "pixelation" and make the text illegible.
• PDF (Compact) vs PDF: Always use "Compact" for emails. Standard PDF files on the MF453dw are often uncompressed, whereas Compact PDFs use a compression algorithm that can reduce a 10MB file to under 500KB.
• ADF Maintenance: If you notice streaks in your "Compact" scans, clean the narrow glass strip (the slit glass) with a lint-free cloth and a tiny amount of isopropyl alcohol; compression often makes dust streaks more visible.
• Email Limits: Most email servers (like Gmail or Outlook) have a 20MB to 25MB attachment limit. If you are scanning a multi-page document, use the "Split PDF" option in the Remote UI to break the file into smaller chunks.