Surveys by both CareerBuilder and Accountemps have indicated that an emailed thank you note is acceptable to most employers in the USA. If you interviewed with a very conservative organization, you should probably consider sending a formal thank you in an envelop with a stamp as a follow up.
If you have had no email interaction with the anyone in the organization, definitely do a formal written thank you.
Like the formal written and printed notes, send a unique message to each person who interviewed you because emailed messages, in particular, are often passed around to others who interviewed you and others in the organization.
[Related: Making Email Work for Your Job Search, Sample Job Interview Thank You to the Person Who Referred You, Sample Job Interview Thank You to an External Recruiter and Sample Thank You Note After a Bad Job Interview.]
If you are employed, do NOT send this message from your work email, your work computer, your work smartphone, or while you are in the office!
Your employer may discover the message and your intentions to leave. The result is that you could have a very uncomfortable discussion with your boss about your job search, or you could lose your job. So, send this message from home using your own personal computer and your personal (not work!) email account.
Leave the TO: field empty until you have completed, spellchecked, and proofread the message (or put your own address in that field until it is ready to be sent).
Send a formal business message.
Don't try to be cute or funny. No emoticons :-( and no texting language (LOL).
[More: Guide to Email for Job Search.]
Replace the Italicized text with whatever terms are appropriate for you and your situation.
Subject: Thank you for the [Job Title] interview on [date]
Dear [Mr./Ms. Last Name]:
Thank you very much for your time today [or yesterday or the date] to interview me for the position of [job title]. I appreciate the opportunity to learn more about this job, to meet you and [names of other interviewers], and to see your facility [or offices, location, whatever is appropriate].
[Reference anything you said that seemed important to the interviewer, like: As we discussed, I find the technology related to using cloud computing fascinating and an amazing opportunity for the future, but security is also a major concern. Keeping XYZ Company's information safe would be a top priority for the person in this job, and I would love to dig deeply into the protective technologies, as well as the threats, to avoid future problems.]
[Reference the "connection" you may have made, like: I enjoyed finding someone else who attended XYZ College and also roots for the hockey team. Hope they make the NCAA Division finals next year!]
As we discussed, I have [months or years] of experience with [technology, tools, or qualification you have that seemed most important in the interview]. With my background and experience, I believe that I could become a contributor to your team very quickly.
I am excited about this opportunity to join [organization name]. Please do not hesitate to email or call me if you have any questions or need any additional information.
I look forward to hearing from you [whenever they said they would be in touch or in 10 days if they didn't give you a date].
[ Your job title or tagline, like "eCommerce Customer Support Specialist"]
[LinkedIn Profile URL]
[Phone number -- not your work number if you are employed]
While email messages are typically less formal than printed and snail-mailed messages, that doesn't mean you should be casual in your attitude or language.
Don't slip into informality, even though this is an email. No emoticons :-( and no texting language (LOL).
[More: Guide to Email for Job Search.]
Hopefully, you will get an email in response to this message, but don't panic if you don't hear from them on their deadline. MUCH may be happening that has nothing to do with you at all. But do reach out eventually to see what is happening
Do NOT contact them daily -- or even weekly -- for a decision.
NEVER suspend your job search while you wait for a decision from an employer, even if the job is your dream job.
[More: The Waiting Game After the Interview - by recruiter Jeff Lipschultz]
While emailed thank you's are acceptable to most employers, I would urge caution if the organization is very formal or "old school" like some old-line law firms, consulting companies, and other similar organizations.
If you have been communicating with them via email, an emailed thank you should be acceptable. But, if you want to demonstrate your understanding of etiquette, send a written version via snail mail, too.
More information: Sending Your Thank You After the Job Interview
Online job search expert Susan P. Joyce has been observing the online job search world and teaching online job search skills since 1995. A veteran of the United States Marine Corps and a recent Visiting Scholar at the MIT Sloan School of Management, Susan is a two-time layoff “graduate” who has worked in human resources at Harvard University and in a compensation consulting firm. Since 1998, Susan has been editor and publisher of Job-Hunt.org. Follow Susan on Twitter at @jobhuntorg and on Facebook, LinkedIn, and Google+.