Them not replying to an email is not your fault. What I would consider someone's responsibility is to follow up and try alternative communications to just sending an email. If that doesn't work then escalate it on your own accord to your team lead. What I would consider not acceptable is sending one email and just blocking any attempts at forward action because you didn't get a response. Quite honestly that type of behavior would make me happy to see you run away screaming.
I understand your position. However from my position it just creates more work for me and balancing between spamming people and being always ready to answer to the teamlead "What happened to X?" and the answer "It's at Joe's" is not acceptable. Anyway, to me it wasn't a healthy environment.
