Letter of Invitation to visit Thailand

I have been asked by a filipina friend to write a letter of invitation. She is coming early in September.
To whom is the letter addressed?
What information, in addition to the dates she'll be here and my address, should the letter include?

Adressed it to Immigration Manila or wherever she departs to..But this doesn't guarantee her entry..It depends on how she answers them incase she will be interrogate..Best also is,she should have a hotel reservation,activity itinerary and a show money incase...again,these documents doesn't guarantee as Immigration Philippines so tight now..It's just a matter of luck and how she can make them believe she's not coming here to look for a job..Good Luck!

In addition to that,You can also send her photocopies of your passport,working permit,visa and statement of account...

She's coming to Thailand from the Philippines. But you're suggesting the letter should be addressed to Philippine Immigration? She would be staying with me, not at a hotel. She has money and has been to Thailand many times. She won't have a problem leaving Manila; I know about problems with Philippine Immigration, have had two filipina girl friends who are living in Thailand now, one lives with me.

I'm just talking about My experienced as My daughter just came here and those are the docs she showed in Immigration Manila when she got interrogated..I'm supposed to get her a supporting letter from Phil embassy but I got no time cuz I'm working..So I took chances and sent them my photocopies of docs..

Letter should be addressed to: "To whom it may concern"