A: Hi Bob,
Thanks for getting in touch.
You can depending on the paper type. Here are the recommended sizes for this printer from HP - Tray 1: A4: 75 to 90 g/m²; HP envelopes: 75 to 90 g/m²; HP Photo Paper: up to 250 g/m²; HP 10 x 15 cm photo paper: up to 250 g/m²
You can also take a look at the brochure for any further information you may need - http://www.printerbase.co.uk/media/pdf/hp-envy-5640.pdf
I hope this helps and please let me know if you have any further questions.
The Printerbase Team