Dear Sir / Madam,
Dear Mr / Ms Jones,
To whom it may concern,
I am writing to make a reservation / apply for the position of.../ confirm my booking / ask for further information about... (making a request)
I am writing with regard to the complain you made on... (replying)
Regarding the... / Concerning the..., I would like to...
Could you please let me know if... / I would also like to know if... / I am interested in... (asking for information)
I am glad to inform you that... (giving information)
We regret to inform you that...
I regret to say that... (complaining)
I am attaching my VC for your consideration / I am sending you the... / Please, find attached the file you requested (attaching files)
I look forward to hearing from you.
Yours faithfully / sincerely / truly
Sincerely Yours,
Best regards,
(signature)
You will find examples on this website: http://www.wikihow.com/Write-a-Formal-Email