This will sound like a broken record, but you should have called, not written, your contact at this company, and asked if the salary was negotiable. You made what I consider to be the mistake of assuming this offer was negotiable. Maybe it was, maybe it wasn' t. Maybe they offered you the bottom of their starting range, maybe they offered you the top (in which case, the salary is like not negotiable).

These kinds of negotiations should be done on the phone or in person, not via e-mail. There is too much left to interpretation--they may assume your attitude is one thing, when you meant it to be another. You already made one too many assumptions, and any further assumptions on their part because you did not speak to them personally may muck up the works.

I personally would wait no more than 3 days from when you sent your counter offer, then call the person to whom you addressed the letter. You can say you just would like to verify that your letter was received, and ask about the status. That' s it at this point. Not much else you can do.

As a general question, why is it that job seekers today seem to feel that a counter offer is expected, should be made, or is acceptable without asking first? I used to be a hiring manager, and though the salaries at the organization were pretty much set in stone and not negotiable, I would not have been upset if a candidate asked if an offer were negotiable. However, if a candidate simply came back to me with a counter offer, without discussing the issue first, I would have been very taken aback by the assumption (not by the desire for more money). Wanting more salary is normal & human; presuming that an offer is negotiable and forging ahead with a counter offer is impolite and nervy. This is not like buying a house or a car, people!