ProtonMail coupons are used to grant discounts on paid subscription plans. Generally speaking, coupons can only be given out by our customer support team, and only for special situations for existing customers (like if we made a billing mistake).
Beware, there are many scam websites offering fake ProtonMail coupons. If you see a ProtonMail coupon code being offered on a website that is not protonmail.com, it is a fake coupon and the site may be a phishing site that is attempting to steal your credentials. Do not visit third-party sites advertising ProtonMail coupons as they may be malicious.
If you have any questions, do not hesitate to contact our support team. If you want to be informed about any official special promotions that ProtonMail may offer from time to time, please follow us on Twitter or Facebook where we post updates.