E-mail and the internet (bulletin boards, forums) have their influence. Until some years back I would never start a reply without 'Dear' or an equivalent. Now-a-days I often only mention the person's name. The evolution (evolution?) is something like this:

1) Dear Mr. Andrews,
2) Dear Michael,
3) Hi Michael,
4) Michael,

In e-mail I often look at the signature of the person who sent me the e-mail. If the signature contains the first name, then I'm inclined to use that first name right away rather than wait 10 e-mails. The first two or three e-mails I'll use method 2. Then I'll skip to 3 and some mails later even use method 4. Though, I'll always check how the other person reacts. There must be reciprocity. Method 4 is interesting and really an invention of recent times (for me, being Dutch). It offers us the possibility to be nice AND not-so-nice. It is extremely neutral, while still making clear to whom the text is targetted.


>Hi Andrews,
>
>Mr. = Mister
>Mrs. = Mistress (e.g. married woman)
>Ms. = Miss (e.g. unmarried woman, but used in US more often than Mrs. since the woman marrital status may be unknown to the caller).
>
>But here in UT I think you don't have to be formal. E.g. you can just call everyone by name, e.g.
>
>Hi John,
>
>....
>
>If you want to be formal, you may say "Dear Sir" or "Dear Ms. " + Last Name of the person. But what if you do not know the gender? Would you write Dear Sir/Madam? I use this form in some of my cover letters, but I doubt it's correct...
>
>
>
>>Excelent answer Mrs. John; I allready got it....
>>
>>Thanks for you help...
>>
>>Keep in toch