If there's no contact information in the sender's email, it could be a red flag. Unless you're dealing with an official Canadian recruitment agency, your job offer letter must come from your employer. Any other communication about your job offers in Canada that comes from an unknown source may be fraudulent. Check if typing the name of the company and the word scam yields any results.
You can report a false job offer to the CAFC and the BBB if you suspect that you have received one. A general rule of thumb is that if you think the job offer is too good to be true, you're probably right. Scammers know that job seekers are in a vulnerable position and are willing to provide their personal information or even money to get a job in Canada. Scammers take advantage of the vulnerability of job seekers to ask them for personally identifying information or even money in exchange for a job in Canada.
Canada also has a job board website where Canadian employers can search for local and international talent.