Does Customer.io host our assets for emails?

Hey! 

Customer.io has an asset library for managing your assets, which makes it easy for you to access them across your messages. You can store bmp, jpeg, png, and gif files for use in your emails, and you can also store PDFs (but please bear in mind that attachments are possible).

This doc goes into some more detail for you:

https://customer.io/docs/asset-library/ 

This should get you in a good spot - let us all know if you have any feedback!

Cheers :)