LegalJob received a question on this topic and this answer was posted in the Monday Mailbag series.

Q:  You talk about how important it is to be responsive on e-mail.  What if I have no information to respond with when I get an e-mail from the partner asking for a status update?

Great example of how important it is to be proactive with e-mail and try to avoid this scenario.  Partners, like clients, (and who should be treated like clients until you have a big book) generally prefer regular status updates.  In general, it is better to e-mail a partner with a status update on your progress on a particular project even if the update has limited or no information.  This practice could prevent an e-mail asking for an update which is obviously less desirable.  In the case you receive such an e-mail, it is important that you respond quickly even if the reply just confirms receipt of the e-mail and explains that you have been working on the matter and have little or nothing to report right now but you will have something soon (i.e., first thing tomorrow and plan to respond again at that time).

Generally it probably makes sense to treat each e-mail as a phone call, particularly early on in your law firm career.  You would not wait more than a day or so to return a phone message and the same etiquette should hold true for the e-mail.   This becomes even more important once you start dealing with clients outside the firm (i.e., not partners) who may believe (or want to believe) they are your only priority.   The timing of the response is likely more important then the content and you can always follow up with more substance in a later e-mail or phone call but a quick acknowledgement of the e-mail may go a long way.