Why it's a bad idea to always have your e-mail open
It's the end of the day. You look at your to-do list. It looks the same as the beginning of the day. How can that be the case when you worked your tail off all day? And you recorded billable time so its apparent you were doing focused work.
A common cause to the untamed to-do list is being in response mode. An easy way to fall prey to that is to be ready, willing, and able to respond to e-mail at any given time of your office hours. There is certainly a reason for doing this; it shows people (clients, other attorneys, the managing partner) that you provide good service, you respond quickly and are available when they need you.
The biggest trade-off I see with this is that you can rarely advance your cases by using e-mail as your vehicle for accomplishing the goals for your client. Even if you are providing answers, updates, or counseling it will mean little in the long run if you aren't moving closer to the closing the case. Sure you can bill for your time e-mailing and it isn't completely ineffective to your practice, but you will get more done if you set boundaries on how you are going to use e-mail in your practice. Once you set boundaries, you will find the time you spend on e-mail gets minimized without any extra effort on your part.
Here are a few boundaries I have established.
(1) When a client asks a question that deals with strategy, a legal analysis or is emotionally-charged then I (a) make a note to call them about their e-mail in a timeframe that is reasonable (no more than 48 hours) or (b) reply and ask if they would come and meet with me in person to go over their questions or concerns and then offer 2-3 times I am available.
(2) I don't send e-mails when a phone call is more appropriate. It will take less time and get things done sooner. Want it to be in writing for your own records? Take good notes while you are on the phone and take a minute or two afterwards and make sure your notes will make sense if you read them a week or a month later. Using e-mail to have everything in writing is a big waste of your time. If you need something to be in writing "just in case I need to prove this was said", I'm certain you can figure out a way to get that result without using e-mail for every communication.
(3) If I'm working on something that needs to be e-mailed, I will draft the e-mail in a word document and then wait until I'm in e-mail mode and copy and paste it into a message.
(4) My to-do list includes people I need to e-mail and I do them all in the same block of time.
(5) I do not give my clients any indication that e-mail is the preferred method of communication and this is done by applying (1) listed above to myself. If I have a client that is high needs, I schedule a reoccurring status call to discuss the health of the case and answer questions.
A top priority for me is to open and close cases as efficiently and effectively as possible. I use e-mail as one of many tools throughout the day (hopefully no more than one hour a day) to accomplish this priority.
If you have had success with putting boundaries on how you use e-mail, I would love to hear about it.
p.s. If you are in a firm where it is expected that you always have your e-mail open, ask permission if you can check it 2-3 times a day for urgent messages and have it closed other times. You can also ask a colleague to alert you if an internal e-mail went out that requires action in the next 1-3 hours.