In today’s internet, data privacy and security is really important. Custom email solutions can be expensive but if you are looking for free private secure and encrypted email service I have two open-source email service recommendations to give that I personally use.
ProtonMail has several paid plans including email services for businesses. But they also have a free version for personal use that includes 500 Megabytes of storage and 150 messages per day. Most personal uses generally do not exceed the limit so you are good to go. As a basic free user you get all the features of security and end to end encryption. Based in Switzerland and all of the data is protected under Swiss Federal Data Protection Act (DPA) and the Swiss Federal Data Protection Ordinance (DPO). In terms of sharing the data, company claims that only very limited amount of data is shared and only if only the company is compelled to by a court order from Cantonal Court of Geneva or the Swiss Federal Supreme Court. They host and manage their own servers. As a free user you can also choose to receive emails using their short pm.me domain.
Tuta and nota literally translates to ‘Secure message’ in Latin. For free and private use they offer 1 GB of storage. For now they have not put a cap on message limit. Messages are end to end encrypted. The encryption take place on user’s local device and the private and public keys are generated via browser upon signup. The private key is encrypted with the account password. Snooping around your address book is also not possible unless you giveaway your password which as a sensible user you would not. They also strip away any geographic information from your email headers including your IP. But they do store IP addresses for a week. In terms of security check, they employ penetration testing.