Skiff Team / 7.04.2022Home / guides

Comparing ProtonMail and Skiff Mail

Skiff Mail and ProtonMail have become widely used, end-to-end encrypted mail providers. How do they stack up in features, security, and usability?
Pink email logo with other email provider logos in grey.
Tens of millions of people are switching from privacy-invasive email providers like Gmail and Microsoft Outlook, but they frequently do not know about alternative secure email services that are available, popular, and easy to use. While there are countless great email clients available today, the privacy-first, secure, and end-to-end encrypted email market is smaller and varies significantly on usability and feature sets. This piece will delve deeper into two of the bigger names: Skiff Mail and ProtonMail.If you have been considering changing your email account to something more private and secure, but have not made the final push, this is the blog for you.


Skiff was founded in 2020 in New York City, with its first product being a real-time document collaboration product that incorporated full end-to-end encryption. In May 2022, Skiff launched Skiff Mail, its fully end-to-end encrypted email service which is already making waves as one of the best alternatives to non-secure standard email products.ProtonMail is a Swiss privacy company founded in 2013 in Geneva, Switzerland. ProtonMail was founded by researchers at the Swiss Particle Physics Research Laboratory CERN. ProtonMail’s first product was a fully end-to-end encrypted email client and service. They have since developed accompanying Calendar, VPN, and Drive products.

Email encryption

The core security features and functionality of Skiff Mail and ProtonMail includes end-to-end encryption of all emails. End-to-end encryption is a system of communication where only the communicating users can read the messages; not even the service provider can read the messages. This is because the messages are encrypted at the sender’s side with a key known only to the receiver. Even if the messages are intercepted in transit, they cannot be read unless the interceptor has this private key. While Skiff Mail and ProtonMail both have end-to-end encryption as the central tenet of their respective products, they implement the encryption in different ways.Protonmail uses the more standard PGP encryption standard; Skiff Mail, on the other hand, uses an elliptic curve based encryption standard that is designed to be more usable, efficient, and scalable than PGP. If you’re already a devout PGP user, or you do not want to consider or manage PGP keys, this particular differentiating feature may make a difference for you. You can read about Skiff’s encryption in their white-paper here.


Unlike other email providers, like Tutanota, both Skiff Mail and ProtonMail offer their users two tiers. The first is a free email tier that anyone can sign up and use without having to input their phone number or previous email account, thereby requiring no personally identifying information on signup. These free plans come with lots of features and functionality, but, if you are looking for a more comprehensive secure email solution, then both Skiff Mail and ProtonMail offer users paid tiers that yield more features, storage space, and more.Skiff’s Pro tier costs $8 a month while ProtonMail’s unlimited tier costs $9.99 a month. These paid tiers will offer more functionality, more gigabytes of storage, priority customer support, and additional features that are not available for free users.

Open Source

When deciding on your secure emailservice provider, it is important to take into consideration how much of your email provider’s codebase is open source. Open source is a term used to describe software that is free and available for anyone to look at, modify, and/or distribute. The term is often used in contrast to proprietary software, which is software that is only available from the copyright holder.Open source software is often seen as a better alternative to proprietary software, as it allows anyone to improve upon it and make it better. Additionally, open source software is usually more secure and stable than proprietary software, as anyone can report security vulnerabilities and they will be fixed quickly.Both Skiff Mail and ProtonMail are dedicated to having an open-source, transparent codebase to ensure users are able to understand and trust the products they use for communication and collaboration.Skiff Mail’s open source code is available on their GitHub page here, including the Skiff Mail product, a UI component library which can be used by other parties, and encryption libraries that are also available for further use. ProtonMail also hosts their open source libraries on Github here.


Today, many of us use our email services as a secondary cloud storage platform. We keep years of sensitive information - including medical, employment, and family records - that we want to store and access from any of our mobile devices or desktops.Skiff Mail offers users with a free account 10 gigabytes of storage, while Skiff Pro users have 100 gigabytes of storage to play around with. Skiff is soon releasing a 1 terabyte (TB) storage plan.ProtonMail free users receive 1 gigabyte of storage, while the ProtonMail unlimited users receive 500 gigabytes of storage.If storage is important to you, but you would prefer not to pay for your email service, then Skiff Mail’s 10 gigabytes of storage might be the perfect fit for you. Otherwise, ProtonMail’s 500 GB plan could be a good fit depending on your use cases and needs.

IMAP/SMTP support

Skiff Mail does not support IMAP/SMTP but does allow users to download free mobile apps on iOS, Android, and macOS (with more platforms coming soon). Skiff Mail is also available on all browsers, which means users should never feel inconvenienced.ProtonMail support IMAP/SMTP through its ProtonMail bridge software. ProtonMail bridge is an application that allows you to use your ProtonMail account with a third-party email client such as Microsoft Outlook, Mozilla Thunderbird, or Apple Mail. ProtonMail’s bridge software still encrypts your email messages end-to-end, so only you and the person you're communicating with can read them.


Skiff Mail is available on all browsers, with iOS, Android, and macOS apps available for download. Skiff also offers iOS, Android, and macOS apps for their Pages and Drive products.ProtonMail is available on all browsers as well as having its own Android and iOS apps available to download.

PGP encryption

PGP (Pretty Good Privacy) is one of the most popular end-to-end encryption methods. It was developed in 1991 by Phil Zimmermann. PGP uses a combination of public-key and symmetric-key encryption. The public key part is used to exchange a symmetric key that is used to encrypt the actual email and other information. PGP can be used to encrypt messages, files, and emails. Because PGP uses asymmetric encryption (with public and private keys), it can also be used to create digital signatures. Digital signatures are created using an individual’s private key, which only the signer has, but anyone can verify the signature using the signer’s public key, which can be shared widely or published.ProtonMail uses the PGP encryption standard as the basis for its end-to-end encryption. Skiff Mail uses its own encryption schemes with elliptic curves, which was largely designed to mitigate some of the speed and complexity issues frequently associated with PGP. You can once more read more about Skiff’s encryption protocols here.

Custom domains

Skiff Mail supports adding up to three domains on the Pro tier and five on the Business tier. These can be configured from Skiff Mail's settings page, with more information on setting up your domains available on our blog.Custom domains are important because they give your email address another level of customization, professionalism, and ownership. They also make it easier for people to find your website because they will be able to remember your domain name. Additionally, custom domains can help you build credibility and trust with your audience.

Purchasing domains

Skiff also rolled out Skiff Domains, where domains can be purchased inside of Skiff from the custom domains settings tab and instantly configured to work with Skiff Mail for privacy-first email and collaboration on your domain. Domains are generally quite inexpensive (under $10.00) and incredibly easy to configure.

Security Features

Both Skiff Mail and ProtonMail support two factor authentication as well as product security features including end-to-end encryption, spam filters to prevent phishing or other malware attacks, image tracker protection, and regular security audits by third parties to ensure there are no security vulnerabilities on their respective software.

Additional email functionality

Skiff Mail support significant additional email functionality, such as the ability to schedule an email to be sent at a future date and time, the ability to unsend an email, setting up an auto-reply response and adding a custom signature to be appended at the end of each email.ProtonMail supports the ability to unsend an email, set up an auto-reply response, add a custom signature and set up inbox rules for incoming emails.Today, there is no disadvantage in user experience in using an encrypted, privacy-first, secure email provider over a standard provider such as Gmail or Outlook

Email aliases

An email alias is an alternate email address that can be used to receive email connected to a single main email account. Email aliases can be used to protect the user's primary email address from spam, separate and organize an inbox with multiple addresses, or simply to provide a more professional email address.Skiff Mail lets users have four email aliases regardless of whether they are on the free plan or on Skiff Pro. Skiff will also soon release a significantly higher alias limit for Pro users.ProtonMail lets free users have a single email alias, while ProtonMail unlimited users can have 15 email aliases associated with their account.

Additional paid features

Skiff offers numerous Business and Pro features across paid plans that make the product well suited to teams and organizatino use. From shared subteams to alias management, Skiff is an excellent organizational product to replace Google Workspace or Outlook. See below for more paid plan information:Here’s a glimpse of our plans:
Drive storage10 GB100 GB1 TB
Sending messages (limit)200/dayUnlimitedUnlimited
Folders and labels5UnlimitedUnlimited
Custom signatures
Auto reply
Schedule or undo send
Email + doc text search
E2EE link sharing
Document limitUnlimitedUnlimitedUnlimited aliases41015
Custom domains025
Workspace collaborators66Unlimited
Doc version history24 hoursUnlimitedUnlimited
Source: @JD LoraxEvery Skiff Mail user gets full access to the following products:
  1. Skiff Drive (with free 10 GB storage)
  2. Skiff Pages (for all types of documents and real-time collaborations)
  3. Skiff Calendar (integrates natively with Skiff Mail)

Other useful features

Both Skiff and ProtonMail have tons of other features besides their core secure email service. Skiff also has a real-time document collaboration product that is fully end-to-end encrypted, as well as a fully end-to-end encrypted cloud storage product for all of users files and sensitive data.ProtonMail additionally has a VPN, encrypted, calendar and its own encrypted drive solution on top of its secure email service.

More secure email providers

There are plenty of other secure email providers in the market besides Skiff Mail and ProtonMail. These included Fastmail, Zoho Mail, Mailfence (OpenPGP email service based out of Belgium), Tutanota (based in Germany), and

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