You can save your incoming invoices as PDF files to your expenses.
iOS
Open the email with a bill or invoice. It should contain either a PDF file or an image
Click on the PDF or Image file to open it
There's an icon of an arrow in a box on the right side (either on top or on the bottom depending on your device) - click on it
A new menu opens. Find Copy to Billdu and click on it
The image/pdf-file will be transferred to your expenses, and you can enter other details and save it
ANDROID
Open an email with a PDF file
Click on the file to open it
From the menu (mostly three dots on the right) select Share
Find and choose Billdu
The image/pdf-file will be transferred to your expenses, and you can enter other details and save it
PDF FILE
Locate the PDF file
Click and hold your finger to display a menu
Select More...
Choose Share
Find and select Billdu