Photos are saved to your camera roll as a safety mechanism in case the photo upload fails. 
This is something we could potentially look at in future. What’s your specific use case? Are you attaching a high number of receipts?
Email receipts capture so much useful information but they’re quite difficult to use in practice. 
@jelmer_snoeck and I did a hackathon project on this and we encountered several road blocks:
- No common identifier we can use to link card transactions with email messages
- Different email servers, protocols (not everyone uses Gmail!)
- No standard structure for receipt data - line items, quantities, prices, pictures etc
- PDFs, attached images, message open tracking links etc
- Requires a user to grant full access to their inbox
Instead for now we’re focused on:
- Specific integrations with a few key merchants e.g. TFL
- Encouraging other merchants (and third-party developers!) to use the Mondo API to enrich their customers transactions e.g. seeing your Nando’s Card balance after a purchase
We’re hoping in future that merchants could even add actions to transactions. But that’s much further away 