We sure do a lot of talking about email. About how to organize your inbox, attain the elusive Inbox Zero or keep your email messages short and sweet. So here we have another quandary for you: Would you send a 3 a.m. email to your boss or a client?

The awesome thing about email is that you can send messages to anyone nearly anywhere, and you can do it instantly, no matter what the time of day.
So sending an email at 3 a.m. should be a novelty of new media, not a reason to stress out. And yet, we find ourselves asking if it's OK to send emails late at night.
We can see two potential problems to late-night messaging:
- It tunes the recipient in to your (lack of) sleep schedule. You probably don't want your boss—or anyone else, really—wondering what you were doing to stay up until the wee hours of the morning.
- It might disturb them if they have loud alerts on their phone. Yeah, we know—if they leave their Blackberry next to their pillow with messaging alerts set to the loudest tone, they've got nobody to blame but themselves. You still don't want to be the one that wakes them up with a less-than-urgent email.
What do you think? Is it OK to send late-night emails? Or do you steer clear of non-9-to-5 conversations? Tell us in the comments!
(Images: Flickr member oso licensed for use under Creative Commons, Flickr member rivalius13 licensed for use under Creative Commons)

Shaw's Original Fir...
If it's for work, I would wait until it's closer to work hours. Even though it's just an email, you don't want to start blurring those lines. What if the recipient is up and decides to respond and then a conversation develops back and forth and now you're both working at 3 in the morning and most likely, not getting paid for it.
With friends, I'll do it if it's something they need to know by a certain time and I'm afraid that I might forget in the morning.
I've worked for organization with offices in other parts of the world - India, for example - so emails were coming and going at all hours, and no one thought anything of you responding to an email at an odd hour.
But forget one anyone thinks of your hours or about waking someone up - don't send emails at 3 am for your own sanity!
working for a 24-7 company, I would have no qualms about it ... unless I had been drinking :)
Here's my concern - I don't want people to expect that I will check my email that late at night. If I write work-related emails at 3am, that gives the impression that I will be checking my work email at midnight and can be expected to get back to people. Which is not the case.
All the time. My most productive hours are 10pm to 1am. No one's ever responded with "how dare you email me this late!?"
My thoughts...
People shouldn't have loud email alerts, if they do that's their problem. I get lots of emails in the middle of the night. Not personal emails, but still.
Who cares if I go to bed at 9pm or 3am? People should mind their own business.
I do IT support for an organization. One Department head is notorious for sending emails to staff members at 3 am. This causes a problem because when the staff arrives for work in the morning, they feel like they're behind in their duties getting data to the supervisor. Plus, whatever they planned to work on that day, get put on a back burner, to meet the new request.
I do not check email after 9pm (I also will not reply to work email on the weekend). I've told my boss many, many times. Yet she still sends "urgent" emails after midnight and gets upset when I don't reply until 8am. Nothing in our business is that urgent. If she wants me to be "on call" at all hours, she can double my salary and pay for a smart phone.
I wouldn't hesitate at all to send a friend an email at 3am. But I certainly would never send an email to my boss before 6 am. I don't want her knowing that I'm staying up all night and I wouldn't want to risk disturbing her. She'd most likely be asleep anyway and wouldn't check it until morning, so why bother sending one at that hour? Wait until a more reasonable time.
The alert noises aren't a concern for me, since, as you said, that's on them to handle.
As for the sleep schedule issue, it depends, as always. Generally speaking, if I have a good working relationship with my boss, my boss respects my space, and I'm confident in my work on the whole, I don't have any issues sending e-mails late at night. Regarding that third point, it's worth saying that it's not a good idea to send out shoddy work late at night, since that just makes the sender look desperate and reflects poorly on them.
Most of it, however, comes back to how professional you keep the relationship. If you maintain distance with your boss and fear that they may try invade your personal life if presented with an opportunity, e-mailing late at night is a bad idea. For bosses with whom you are more friendly, and who you can trust not to abuse knowledge of that sort, then e-mailing late isn't an issue, and can be an indication to them that you're committed to and interested in the work you do. As long as they don't come to expect it, it benefits us both, since the work gets done when it's most convenient, and they appreciate having a response back that much sooner.
Dude, the entire point of email is that it isn't as intrusive on other people. Frriggin' send when you need to send (or, put to use the magical novelty invention known as the DRAFT and send it later if you're so deeply concerned about it!). My goodness do we overthink things sometimes!
I would save it as a draft and send it in the morning.
My late night emails and other work have demonstrated that I don't just work when I'm in the office. As a result, my employer is comfortable with giving me flex time (first employee ever) and I survived this year's budget cuts.
My most productive time is also 10pm-2am; I wouldn't get nearly as much done if I didn't work during this time.