If you're sending to a list
It's a list, but the main person changes with each date. As impersonal as an email is, I like the "To:" to be the birthday person. Everyone else is in "Bcc:". I just copy two parts of the 'email' column in the spreadsheet and paste. I'm just stubborn and cheap!
I don't use Google, nor Gmail.
I refuse to surrender!! I'm assuming that you mean...VPN
True, my keyboard maid a miztake.
I just today got a note from MailButler asking if I needed more help with their app. I didn't bother suggesting that they put the "Send Later" function in the free option.
Still 'thinking' about Automator/AppleScript. The sending part is actually the easiest of the tasks. Coming up with something at least a bit personal for people, most of whom I haven't talked to for over 55 years, is more difficult.
At least some of them have 'bio's' at the class web site. At our age we will probably not remember what the email said 365 days ago!