If you looking for employment, you may not be able to email from the job you're at during the day.
The potential employer will know you're emailing on your own time.
Correct re phone calls.
I get people returning my calls, leaving me VM's at 7pm or after, like they seem surprised I'm not there.
I don't mind when they leave a message saying they are acknowledging my call, and will call back in the morning, although that's useless and a waste of time IMO. The one's who leave a message, especially on a Sunday afternoon, like they thought I would be there, are really annoying.