1. Using speaker phone when others can hear you. Playing back your voicemail messages on speaker phone or conducting an entire call on speaker phone is distracting to people trying to work around you. Even if you're in an office with the door closed, speakerphone noises tend to travel. Don't value your hands-free convenience over the ability of others to focus on their work.
2. Keeping your cell phone out so you can glance at it during meetings. Glancing down at your phone while you're supposed to be focused on a meeting signals that you're bored, not fully engaged, or don't respect the time of the people you're meeting with. If you must keep your phone out because you're expecting an important call or text, explain that at the start of the meeting so that people don't assume you're just being rude.
3. Don't overuse "reply all." When multiple people are included on an email chain, they don't all need to see your reply of "thanks" or "will do." Only use "reply all" if everyone included truly needs to see your response; otherwise, stick with "reply" so your response goes only to the sender and doesn't clutter multiple in-boxes.
4. Don't email and phone with the same message; pick one or the other. Nothing is more annoying than starting to read an email, only to have the email's sender pop his head in your office to repeat the same message.
5. Turn off your cell phone's ringer if you leave it behind while you're away from your desk. Ask any office worker, and you'll hear stories about the annoying guy who leaves his phone behind with his ringer on full-volume while he goes to meetings … leaving his co-workers forced to hear repeated renditions of "Who Let the Dogs Out" or whatever else he's chosen for his ringtone.
6. Placing calls from a noisy location. If you make a call, ensure you're somewhere where you and the person you're speaking with will be able to hear each other—and where you can give your full focus. It's irritating to get a call from someone who immediately puts you on hold to order coffee because she just reached the front of the line.
7. Keep religious and political messages out of your email signature. Including religious or political messages is likely to offend or at least irritate some of your recipients, and introduces topics that don't belong in a professional setting. Keep your sign-off neutral and professional.
8. Don't use your work email as your personal email. In most offices, sending occasional personal emails from your work account is fine, but you should use your personal account for most personal things. If you treat your work email as your default personal account, chances are good that when you leave your job and your inbox and sent folder are full of personal messages, one of your co-workers will be stuck reading through all of them, as they clean out your account for your replacement. In the best case scenario, that's merely a nuisance for a co-worker —but in the worst case scenario, it could lead to embarrassing revelations.
Alison Green writes the popular Ask a Manager blog, where she dispenses advice on career, job search, and management issues. She's also the co-author of Managing to Change the World: The Nonprofit Manager's Guide to Getting Results, and former chief of staff of a successful nonprofit organization, where she oversaw day-to-day staff management, hiring, firing, and employee development.