OK… REWIND!!!  Let's go through the appropriate steps that will tell you When to Stop Following up after an Interview(and after reading this you will have followed up properly as well).

During the Interview:

• During introductions at the beginning of the interview, write down the name(s) of those interviewing you (if you're like me, you'll need to revert to them during the day anyway)
• At the end of the interview, thank each person by name.  Ask for a business card.
• If you walk out without a business card, ask at the front desk if they have one or ask for correct spelling of persons name and email if they don't have cards.
• With the person in charge of the interview process (HR or Manager) ask what is the process for the company to make decisions.  Ask timeframes and ask if it's ok to follow up and with whom.

After the Interview - Now the timeframes of this might be different based on types of position. For instance, if this is a sales interview you are expected to follow good salesmanship abilities with your followup and process. All of this might be part of the interview so frequency and process is all the more important.  If you're in an auditing or software development position, the timeframes may be a little different for followup, so follow closely.

• Email versus Snail Mail -  I'm a believer in both.  it's what you do different than others that will keep them in mind.   Follow up immediately with a personal email to each interviewer to personally thank them for their time and how excited you are about the position.   Keep it brief and to the point.
• Within 2 business days (48 hours), immediately is preferred, send out a personal letter or Thank You card.  If you write well, handwrite it. If you write like a doctor's prescription, use paper and use your word processing software to type and edit the letter.  You will personally sign either though.
• If the interviewer said a certain date a decision is to be made, say Thursday, follow up on Friday (give time for your letter to have gotten there).  Call the person, reintroduce who you are and since they gave you permission to call, remind them of that.

If you got the job, be excited. That's ok.  It's a happy moment for All!!!  HOORAY!

If the person says they have not made a decision yet, go through the process of asking again; what is the process, are they looking at new candidates(not a good sign if they are) and what are the new time frames.  Ask again, 'May I follow up?".  If you're in a sales interview you better be more specific by asking:

    "What day will you be making the decision?"

    The person replies "We hope to have  decision by Wednesday of next week"

   You ask " May I call you on Thursday or is Friday better? Will 2pm work for you?"   Then follow up at that time. 

Now here is where it gets difficult. You haven't heard yet.   The person was not there when you called.  Now don't  panic just yet.  Many employers take their time today and many things can be happening but now you don't want to appear like an impatient, desperate person but you also don't want moss to grow on the job either.

I recommend if you're in sales, a combination of emails and then a phone call every 3 days or so will keep you in front of them.    What are you saying?  Be helpful. Provide industry info, what other jobs y ou are going on, how you can improve their sales, what you see happening in the market, etc…   but also, what can you do to help them with their decision.

if not in sales, at the end of each week, send an email or follow up with a call, or both.   Don't be too desperate but stay on them as well.

Overall, after 3-4 weeks at the latest if they haven't gotten back to you, send them one more formal letter.  Thank them for their time, remind them why you were the best candidate but also let them know you know they probably found other candidates and you wish them the best of luck.

Keep it professional and friendly. You never know when you may see them again.