Should contractor experience be in Reference Letter ?

[t6e4m8]

Hi,

I worked 6 months in my company but my tax slip was T4A, so that won't count. Then I became an employee on T4 and worked for 1 year. For the reference letter, should I mention all experiences or just the 1-year eligible experience? Also, my company's letterhead doesn't contain email, only address and phone. Is that ok? should I add email to the letterhead?

Thanks in advance.