The coloured envelopes will be delivered to households as the programme progresses though the different groups on the Joint Committee on Vaccination and Immunisation (JCVI) priority list.
The letters will include information on how to reschedule an appointment if it is not suitable.
The Scottish Government says it is “on track” for all those aged over 80 to have received their first dose of the vaccine by the end of the first week in February.
No-one aged 80 or over should expect a blue envelope because they will be contacted directly by phone or letter.
A new booking system is being used by health boards in Fife, Forth Valley, Ayrshire & Arran, Lanarkshire, Greater Glasgow and Clyde and Lothian to schedule appointments for patients in order of priority.
More health boards are expected to make use of the technology as the vaccination programme expands.
Health Secretary Jeane Freeman, said: “We all know how easy it is to ignore some of the mail which comes through our letterboxes but these blue envelopes will be very distinctive and they will contain details of your vaccine appointment so please open them.
“The letters are being posted First Class and we have been advised by the Royal Mail that the colour will allow them to prioritise delivery.
“The blue envelopes will contain information about the time and place of your appointment and details on how to reschedule it if you are unable to attend.
“I would urge everyone to take up their appointment when they are offered one.