An invitation letter is usually needed if you are going to Canada to visit a friend or family member.  All you need to do is ask your friend to send you an invitation letter.  Send them all the information about yourself and let them write the letter.  I suggest that you ask them to mail the letter to you by regular mail, then you can place the letter with the stamped envelope in your application package.  The stamped envelope is important because it makes it shows some form of authenticity.  However, before mailing out the letter, ask your friend to scan the signed letter and send a copy to you via email.  You will use this copy if you do not receive the mailed letter on time.  My friends and family have used the scaned copy a couple of times and it has worked for them.  However, I suggest that you use the original copy if possible.  You may consult the Sample Business Invitation letter for a letter to come for a conference.

When I wrote my first invitation letter a couple of years ago, I did not have a clue about what should be on it.  So I went to the Canada Immigration website and I found a guide.  You can find the guide here - Invitation letter quide from Immigration Canada.

In summary the following should be on the invitation letter.  This list is addressed to the person writing the invitation letter.  Simply send them a link to this page all should go well.

Your letter must include the following information about the person being invited:

* Complete name.
* Date of birth.
* The person’s address and telephone number.
* Your relationship to the person being invited.
* The purpose of the trip.
* How long the person you are inviting intends to stay in Canada.
* Details on accommodation and living expenses.
* The date the person you are inviting intends to leave Canada.

Your letter must also include the following information about the person writing the letter:

* Complete name.
* Date of birth.
* Address and telephone number in Canada.
* Occupation.
* Whether you are a Canadian citizen or Permanent Resident
* A photocopy of a document proving your status in Canada.  For instance, a Canadian birth certificate if you were born in Canada or a Canadian citizenship card if you are a naturalized citizen.  If you are Permanent Resident, you must send proof of your permanent resident status (a copy of your PR card or your IMM 1000 proof of landing).


Visit this link to view Canada Invitation Letter writing guide
cic. gc. ca/ENGLISH/visit/letter. asp

Thanks for sharing such a Informative guide about canada immigration in this thread. This information is really useful and It will really help me in my immigration process to canada.