...
We also recommend that you ensure your document size is set to 8.5 x 11. You can check this in Adobe Reader by clicking File->Properties->Page Size. Oftentimes scanned documents will exceed these dimensions which can cause failures with the Email-to-fax service. The specific error you will receive is: TIFF/F format is not compatible. To overcome this potential problem, you can use a third-party program such as Cute PDF to re-save the file before attaching it. Cute PDF has a default size of 8.5 x 11 so the only thing you are doing when using it is shrinking whatever document you have, to fit the standard paper sized used in most fax machines. You can download the open source Cute PDF program here. Once you have installed Cute PDF you can re-save the file by opening the original PDF file in Adobe, clicking File>Print (or alternately, CTRL+P) and choosing 'Cute PDF writer' at the very top of the resulting window under the 'Printer' drop down menu. Clicking the 'Print' button will cause the normal Windows dialogue window to open asking for a Save Location. Choose your desired location and click the 'Save' button. You can now open the file from the saved location, check the properties in Adobe Reader as before and see the document size is now 8.5 x 11. You should now be able to email this file without receiving the TIFF/F format is not compatible error.
Original File->Properties
File->Properties after re-saving with Cute PDF
...
Your email domain must have a SPF record configured. (For more information regarding SPF Records, click here).
Valid attachment types are:
...