Originally Posted by number_6

As for the original question of what routes require paper, there is no list and it changes all the time (sometimes irrationally). In general small secondary airports lack e-ticket retrieval capability. All OW airlines claim to have full e-ticket capability implemented. In the past I've run into absurdities like BA can issue e-ticket on BA codeshare of AY flight, but AY requires paper ticket for the AY code on the same flight. This seems to be slowly improving each month, with e-tickets everywhere.