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The 6 most secure email clients for collaborative teams
Blog →
by
Eva Tang
September 16, 2025
· Updated on
There are lots of secure email clients on the market—Tutanota, ProtonMail, StartMail. But many of these fail to have the helpful collaborative features of more modern business email clients. Where you can have internal comments, real-time drafting, powerful automations, all in an intuitive interface.
Tutanota - Tutanota is a top tier secure email provider. It offers end-to-end encryption, send encrypted emails, but zero collaborative functionality or third-party integrations.
ProtonMail - ProtonMail is a close competitor to Tutanota. It allows you to send password-protected encrypted emails, open source mobile apps, but no collaborative features.
StartMail - StartMail is another secure email provider. It offers local storage with ISO 27001 certified data centers and out of the box phishing and spam protection, but like the other two options, it has little collaborative functions.
If you just need a few shared labels, email aliases, and calendars to make your team more productive, then any of these options would work great. But if you often have multiple team members working on email threads and/or high volumes of emails that need to be coordinated amongst multiple people—you'll want to look into true collaborative email clients.
If you rely on email for your business and you work with sensitive information, you'll want to know which of these shiny collaborative email clients have robust security and privacy standards underneath the hood.
Note: If you require a very high level of privacy like PGP, you're better off with one of the traditional options (i.e. Tuta) or Mailfence/Posteo/Zoho Mail for small businesses. But if PGP and full end-to-end encryption is not required, then keep reading on...
We looked at 6 of the most popular email clients for teams on the market, and scored them on 6 criteria:
As a benchmark, we compared each of them to the gold standard of secure email providers and email security—Outlook/Microsoft 365.
Let's get into it.
Outlook is the most popular email service and email client for enterprises, especially those who deal with sensitive client information over email. Outlook has unmatched configuration options and incredibly detailed auditability.
Auditability is particularly important for professional industries like healthcare, finance, and public sector companies which have recording keeping requirements by law. Here's Outlook's score:
Bottom line: There's a reason why Outlook is the email service of choice for enterprises. Now, if only they could do collaboration well.
Missive is a collaborative inbox designed for teams that supports all email service providers, including IMAP accounts. While it doesn't offer end-to-end encryption, it does have very high security standards, auditability, and external verification.
Price: Starts at $14/user/month, paid annually.
Bottom line: Missive checks the boxes that most teams look for (SSO, SOC 2, TLS encryption) and is clear in public docs. Audit depth & residency options aren’t M365-level, hence the gap.
Superhuman is a productivity-first email service build for high volume inboxes who loves shortcuts. It offers less collaboration functionality than others on this list, but it shines on it's access/removal functionality. By default, Superhuman does insert a pixel in all emails for it's read receipt feature, that might be a privacy concern for some.
Price: Starts at $25/user/month, paid annually.
Bottom line: If you already run Okta/Entra and need fast onboarding/offboarding, Superhuman’s Identity and Access Management system is excellent. Balance that with the privacy policy’s scope.
Hiver started is the Gmail-only option on this list. It has a a lot of the collaborative email functions like Missive but most of their customers use it as an alternative to a help desk. Here's how they rank from a security perspective:
Price: Starts at $19/user/month, paid annually.
Bottom line: If your priority is “don’t duplicate email content in another vendor,” Hiver is attractive for Google Workspace shops.
Shortwave is the most AI-forward email service on this list. They don't excel at any security standard compared to the other options, but they're a good middle ground option if you're looking for some thing with a lot of AI functionality and you're not required to have solid audit logs.
Price: Starts at $24/user/month, paid annually.
Bottom line: Great in Google-first orgs, but if you need audit trails for compliance/forensics for your industry, you'll probably want a different option.
Spark is used by individuals and teams. They offer a familiar interface with some collaboration functionality, though they are the lightest security option on this list.
Price: Starts at $4.99/month for individuals and $6.99/user/month for teams, paid annually.
Bottom line: Individual teams that want a polished client and understand the implications of server-side features for notifications/scheduling.
Tuta, ProtonMail or even Zoho Mail has a lot of the enterprise-grade security features (encrypted mail, PGP, etc) right out of the box, but the collaborative-first email clients we mentioned here might be able to meet your security standards with a little custom development. For example, you can feed all of the data/comms out to a third-party compliance service to make sure you hit the regulatory requirements.
At the end of the day, it'll depend on what trade offs you're willing or unwilling to make. Most businesses want some level of security but also usability and collaboration. How much of each will depend greatly on your use case.
Which of these options offer end-to-end encryption and encrypted emails?
Short answer is none. While most of these options have some form of encryption, the higher scoring ones are encrypted via TLS at rest and in transit, but none of them offer the same level of encryption features as Tuta or ProtonMail.
Is Outlook “more secure” than these tools?
It’s more controllable out of the box—especially for audit, labeling/IRM, and data residency. That’s why we use it as the baseline. Your best option is the one that fits your constraints and is configured well.
Do these tools read my emails?
Policies differ. Some tools process email content to power features (e.g., read receipts, scheduling, AI summaries). Some store only metadata. Always confirm what’s stored and for how long.
Are there other options with different encryption options?
If you're primarily looking for encryption features, but don't want to go with your standard Tuta, then you might want to check out Zoho Mail, Mailfence, or Posteo. The latter options offer OpenPGP end-to-end encryption and the former is basically enterprise level controls that isn't Outlook.
May 21, 2025
Collaborate beyond your team: Guest Access is here
We designed Guest Access for anyone you occasionally collaborate with (think your accountant, a third-party vendor, seasonal workers, etc).
Remember the first time you @mentioned a teammate below an email, instead of forwarding it to them?
That’s a magical moment for many Missive users.
It’s when they realized email can be collaborative without creating more email.
Starting today, with Guest Access, you can give that same experience to anyone you work with — even if they’re not on your team.
Guest Access makes it easy to bring people outside your organization — like an accountant, contractor, or client — directly into specific Missive conversations.
No more forwarding long threads. No more stitching together feedback from different tools. Just real-time chat alongside the emails that matter.
Here’s how it works:
Your guest will get an email with a link to join. Once they create a free Missive account, they’ll land directly in the conversation you invited them to.
They’ll be able to read the full message history and reply via chat — but not email, tasks, or assignments. Just focused, limited access.
Guest Access is included in all Missive plans. No add-ons. No hidden costs.
Each team member can invite up to 5 guests, and each guest can access up to 5 conversations.
That means if your team has 10 users, you can collaborate with up to 50 guests across 250 guest-enabled conversations — all for free.
We designed Guest Access for the people you don’t work with every day, but still need to collaborate with effectively — without paying for a full seat or dragging another tool into the mix.
If you’ve ever said:
I wish this person could just see this conversation—now they can.
Guest Access isn’t just for external vendors or partners. If you have teammates who don’t need full Missive functionality every day, Guest Access is a perfect lightweight option. No need to buy a full seat just to loop someone in occasionally.
By default, any team member can invite guests. But admins can manage this in:
Settings → Guests → Allow guest invitations
You can:
Want tighter control? You can restrict guest invitations so only admins or the org owner can send them. That way, access stays centralized and intentional.
Guests can:
Guests cannot:
This keeps their access simple, focused, and secure.
Admins can see which guests are active and what they have access to. If you need to invite new guests but hit your limit, you can quickly revoke access from inactive ones to free up slots.
We can’t wait to see how you use Guest Access.
Whether you’re looping in a freelance designer, a tax advisor, or just a teammate who doesn't need a full Missive seat — Guest Access gives you the power to collaborate where the conversation is happening.
Try it today and let us know what you think!
Can guests see the full history of the conversation?
Yes. Guests can view the entire message and chat history of any conversation they’re invited to.
Can guests reply to emails or send new ones?
No. Guests can only send chat messages. They cannot interact with the email side of the conversation.
Can guests be assigned to tasks or create tasks?
No. Guests don’t have access to task-related features in Missive.
Can guests @mention team members?
Yes. Guests can use @mentions in the chat area of the conversation to address specific people already present in the conversations. They can’t @mention people not present in the conversation.
What happens if I remove a guest from a conversation?
They will instantly lose access to that conversation and all its content.
Can I re-invite someone after removing them?
Absolutely. You can revoke access at any time and re-invite them later if needed.
Can I upgrade a guest to a full team member later?
Yes. If someone needs broader access, you can always add them as a regular user by assigning them a seat.
What if my guest has their own Missive organization?
They will be able to access the conversation(s) that you granted them, from their existing Missive interface. It will be treated like any other conversation.
November 29, 2024
Google Collaborative Inbox: Why Your Teams Won't Like It
Google's Collaborative Inbox offers a way to manage shared email addresses, but it has some flaws.
At its core, email was designed to be addressed to a single individual, just like regular mail.
But with more and more businesses starting to increase their online presence, catch-all email addresses (info@, sales@, support@) began to increase. And with no way to efficiently distribute the workload of these catch-all addresses, email quickly became a burden. To resolve the problem, it wasn't uncommon to see people use the oldest hack in the book:
Sharing individual account passwords.
It might have worked very early on when online security was not a big thing for most organizations. But email providers, like Gmail, quickly started dissuading this practice by temporarily locking people's accounts when detecting multiple sign-ins to the same account. As an alternative, Google offers Google Groups and its Collaborative Inbox.
But what is it exactly? And is it the solution you’re looking for? Let's find out!
Google Collaborative Inbox is a free feature of Google Groups available to businesses using Google Workspace (also known as G Suite). It can be used by teams to manage shared email accounts that are meant to be shared mailboxes, such as support@ or info@.
While not a complete shared inbox software solution, it offers more robust features than Gmail when it comes to email collaboration.
To simplify things, Google Collaborative Inbox is a shared email folder that members of a group can access through their own accounts.
The idea is that group members can access a shared email address securely. All members can email everyone in the group and can also allow external emails. They can assign conversations to different group members, mark the progress, create labels, and filter them.
It’s the simple evolution of a distribution list, allowing teams to somewhat collaborate around a shared mailbox.
Google Collaborative Inbox allows teams using Google Workspace to access a basic shared mailbox without the need of other software.
It can be used to manage email addresses that need to be accessed by a group of people. The benefits of using Collaborative Inbox come mostly from the collaborative nature of the feature and not the tool itself.
Here are the benefits of a having a shared mailbox with collaboration functionalities:
Google Collaborative Inbox sounds great, but according to its users, the solution is complex to use yet limited in its features.
Your customer support and sales teams will certainly be the most impacted. Here are the most important ones:
The UI is unfamiliar and doesn’t integrate into the Gmail inbox. So your team will have to shuffle between the two apps. It also means that you can't manage all your email from one place.
You cannot easily discuss an issue with a coworker in the context of an email. Nor can emails truly be delegated. You need to either forward emails, which will generate more emails, or use the built-in chat, but you will need to describe the problem since your message won't be in context.
Replies to customers are sent from the individual's account, not the group email address, so you always need to remember also to send them to the group address. Otherwise, teammates will no longer see that email. And if the customer forgets to "reply-all", the email will never show up in the group's inbox. Emails can easily fall through the cracks.
If an email has been assigned to someone, other people won't see if others are already working on it, not until the reply is sent. This may lead to double responses, wasted time for your team, slower response time, and customers getting a negative impression of your organization.
There's no simple way for a manager to monitor emails from their team. Filtering is also a bit rudimentary, so important things might get easily overlooked.
You also need to switch between Gmail and the Google Groups UI to be on top of things. This also means that emails sent to the group address can't be read on mobile devices, because they cannot be accessed through a Gmail account or any other app.
Creating automation rules that help your team triage emails faster is impossible. Everything needs to be done manually, which can lead to mistakes.
You can't centralize your team's communications. As we all know, customers nowadays contact organizations through various channels, like, Messenger, Instagram, SMS, etc.
To wrap things up, we could say that using Google's Collaborative Inbox is far from the right tool for the job. Lost emails, unclear ownership, unintuitive UI... Here's where Missive might prove to be an excellent weapon to keep in your arsenal.
You want to give Google Group Collaborative Inbox a shot?
Here’s how to (relatively) easily turn on the collaborative inbox features in Google Groups:
Managing the workflow of a Collaborative Inbox inside Google Groups can be done in a few different ways. Depending on the permissions you gave to each team member they can use Google Groups features to manage the shared folder of email.
You can assign a conversation to any group member including yourself to manage messages and responsibilities. Conversations can be sorted based on their assignment status.
You can mark a conversation as complete, no action required, or as a duplicate. Right next to the subject will be the status of the conversation.
You can organize your Collaborative Inbox by using labels on related conversations. Labels can be used in conversations no matter their assignment and resolution status.
Your best option when looking for an alternative to Google Groups’ Collaborative Inbox is dedicated email collaboration software for business.
While you have multiple options (refer to our top shared inbox software), we believe that this short list of alternatives are the ones that will check all the boxes to make your team love shared email.
Missive is a real collaborative inbox. It features team inboxes and chats that empower teams to collaborate not only around email but other channels of communication like SMS, WhatsApp, Messenger, Instagram, and live chat.
Missive was built with collaboration in mind.
The Team Inbox lets you collaborate with team members and assign them to conversation. It is useful for teams who want a "triage" step that will clean up messages for all coworkers at once.
It lets you communicate with coworkers right inside an email thread. You can also @mention a colleague and start a conversation, all without leaving the email in question.
With Missive, you can create sets of rules that automate actions; these can save time and spare support employees from doing repetitive tasks. For example, all refund-related emails can be automatically assigned to the Finance team or a specific employee.
Price: Price: Free for up to 2 shared accounts. Starting at $15/month for more.
Gmelius is a good alternative for users that want to keep on using Gmail. Gmelius is a Gmail add-on that brings shared inboxes directly to the web app. It comes with features like chats with your coworkers in an email thread, adding labels, and assigning team members to an email.
Gmelius also offer Kanban-style board for project management directly in Gmail.
Price: Start at $15/month
Hiver is another solutions that is used on top of Gmail. This Chrome extension enables you to collaborate and manage your shared inbox in your existing Gmail account. It offers the standard shared mailbox functionalities such as assigning people to a conversation and tagging emails and comments privately in a discussion.
Hiver also comes with features like task automation and analytics.
Price: Starting at $19/month.
Helpwise is a good alternative to Google Group Collaborative Inbox. It offers a shared inbox similar to Missive, with a way collaborate on a shared alias with a focus on shared accounts like SMS, social media, and live chat.
It also lets you add an assignee to a conversation, tag emails, and chat with your coworkers.
Price: Free for 1 shared account. Starting at $15/month for more.
Help Scout is primarily a helpdesk software, but it can double a good shared inbox solution with features like live chat, and a knowledge base.
With it, you can manage shared emails, group emails together using labels, assign people to a conversation, chat with teammates, and tag conversations.
Price: Starting at $25/month.
Don't get me wrong. Gmail is a great email client for individuals. But when it comes to shared inboxes and team collaboration, Missive helps your team keep their eyes on the ball and move toward inbox zero.
Google Collaborative Inbox is a free feature of Google Groups that lets businesses using Google Workspace manage shared email addresses like support@ or info@ as a team.
A Collaborative Inbox is a feature of Google Groups that enables teams to collaborate on shared emails like info@. It acts as a shared folder where all emails from a shared alias go. It offers bare bones and basic shared inbox features.
Shared inboxes allow multiple coworkers to access email simultaneously. While each user maintains a personal account, their shared mailboxes can be accessed and managed by all.
