how do I know if my mugs are ovenproof

[happypotamus]

This might be a stupid question, but I have a recipe for pies baked in mugs. It say spoon the filling into ovenproof mugs. Are all mugs ovenproof? If not, how would I know? Will it make a difference if they have pictures on? I was thinking mugs should be ovenproof because they are made and then fired in kilns but will the picture be ok?

Put them in the oven, you’ll soon know if they’re not.

They should be fine, just don’t put them in too high a temp.