postdocs - What does it mean if a professor does not answer your email in time?

I recently joined a research group as a postdoc. I wrote the professor an email to ask quick but important questions including asking him when when he wanted me to start. It's been over a week and I haven't received get an answer. Other emails I've sent previously have also gone unanswered for long periods as well.

With that background, my question is: do professors sometimes (intentionally or otherwise) not respond to emails in a timely manner?

Answer

I wrote him an email to ask quick but important questions, like, when do you want me to start. I didn't get an answer even after a week. And similar things happened before as well.

Some professors are notoriously bad in answering emails. This does not necessarily mean anything. Don't fret about it.

So I want to ask that as a professor, sometimes will you (on purpose) to NOT answer emails in time?

I'm not a professor, but, no, this is not how I would expect an adult person (in a management position, none the less) to behave. If the professor is indeed having second thoughts about you and decided to just not answer anymore, I would say you dodged a bullet there.

However, I really think that this is unlikely. Just send a polite reminder, or propose to have a quick chat e.g., over Skype, at a time of the professor's convenience.