I am a freelance software developer and have three clients that I communicate with via email. I have mobile and desktop notifications set up for my several email accounts (work, personal, university).
If I see an email notification, I will generally stop what I am doing in order to respond, even if the email is from a client that I am not currently doing work for (I stop/start my clock accordingly). My average response time is about 5 minutes if I am currently in a situation where I am able to respond to an email.
I feel that I have given my employers the impression that I am always available. Should I be waiting an hour (or a few) in order to respond?