You can add images directly to invoices; those will be saved in the invoice itself.
To learn more about how to add an image take a look here.
Other document types, such as PDF documents, XLS sheets or different document types can be sent with an email as attached files.
iOS MOBILE APP
- Select a document and click on Email
- A new window with the iOS Mail App pops up
- Click on the email message (or hold your finger for 1 second on older iOS versions)
- A menu pops up
- Select the arrows to Add attachment, Add document or Insert photo or video
- Locate the desired attachment to attach it to your email message
- Learn more about the process on Apple's user guide
- Click on the Email icon to send the chosen document
- A new window Send by mail pops up
- Click on Choose file
- Locate the attachment you'd like to add to your email message
- You can add any files with a max. size up to 5MB (together)