POP3, IMAP or Exchange? Which mail protocol is right for my company?

For most companies, the best option is Exchange, today almost always in the form of Exchange Online from Microsoft 365, or an equivalent solution such as Google Workspace: email, calendars and contacts are synced across all devices. IMAP remains a good option for small companies that only need email, while POP3 is no longer recommended for companies, because it doesn’t sync messages between devices.

Email has become irreplaceable. Whether you use a browser or a dedicated program, every line of business needs to exchange emails.

In this article, we present the advantages and disadvantages of the three email protocols most used in companies.

Ready? Let’s begin.

The POP3 protocol: Post Office Protocol, version 3

The POP3 protocol appeared in the late 1980s (the current standard dates from 1996) and works like this: the email program connects to the server and downloads the messages, which are then deleted from the server. Some programs can be set to keep a copy on the server, but even then syncing remains limited.

Main advantages:

• It doesn’t require software licenses, because the servers can run on Linux, which is free.
• It can be set up on all devices.
• It’s simple to implement at the server level.
• It doesn’t need much storage space on the server, because messages are downloaded locally.

Disadvantages:

• Downloaded messages are deleted from the server, so there’s a risk of losing them if the device the email was set up on breaks down or is compromised.
• Sent messages aren’t stored on the server.
• There’s no syncing between devices: a message read on one device shows as unread on the others.

IMAP: Internet Message Access Protocol, version 4

IMAP is the standard protocol for email hosted with hosting providers. It offers all of POP3’s features, but also allows syncing between devices. Messages downloaded by the email program also stay on the server, so a message read on one device shows as read on the others too.

Main advantages:

• It doesn’t require software licenses, because the servers can run on Linux, which is free.
• It can be set up on all devices.
• It’s simple to implement at the server level.
• All messages are stored on the server.
• It allows syncing between devices.
• It lets you create folders directly on the email server.
• It stores sent messages on the server.

Disadvantages:

• It needs more storage space on the email server.
• Once a message is deleted from the email program, it’s deleted from the server too.
• It syncs only email: calendars and contacts need other protocols or other applications.

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Microsoft Exchange

Exchange is the email platform developed by Microsoft. Simply put, it’s a kind of “IMAP” designed specifically for business. Besides syncing emails between devices in real time, it lets you use and share calendars and contacts, which makes teamwork easier. Today, most companies use Exchange Online, included in Microsoft 365 subscriptions, rather than an Exchange server installed on site.

Main advantages:

• Messages are downloaded to the email program, but they also stay on the server.
• It integrates very well with the Office suite apps and with Teams.
• Sent messages are stored on the server.
• It lets you create folders, which are also saved on the email server.
• Calendars, contacts and shared mailboxes sync on your computer, on your phone and in the browser.
• Licenses are bought for each email user individually.

Disadvantages:

• Higher licensing costs compared with IMAP servers.
• The initial setup requires solid technical skills, especially for a server installed on site.

What has changed since 2021?

Since October 2022, Microsoft has turned off simple authentication with just a username and password (basic authentication) for POP3 and IMAP in Exchange Online. Email programs now connect using modern authentication, which is compatible with two-step verification.

Exchange Server 2016 and Exchange Server 2019 haven’t received security updates since October 14, 2025. Their successor is Exchange Server Subscription Edition (SE), available on a subscription basis. An unpatched Exchange server is an easy target, as the 2021 attacks on Exchange servers showed.

What should you choose for your company?

• Microsoft 365 (Exchange Online), if you use the Office apps and Teams and need shared calendars. See also how to work from home with Microsoft 365.
• Google Workspace, if your team already works with Gmail and Google Docs.
• IMAP with a hosting provider, for very small companies that only need email. Make sure you have antispam filtering, encrypted connections and backup.
• POP3, only in special cases, for example for archiving a mailbox. We don’t recommend it for day-to-day work.
• Exchange Server on site, only if an application or a regulation requires it. The server has to be updated every month and monitored.

Whichever option you choose, turn on two-step verification, configure your company’s domain correctly (SPF, DKIM and DMARC), and keep a separate copy of your messages, for example through Backup as a Service.

We hope this short guide helps you make the right decision. We’re here for you if you need support or IT consulting to move your email.

RezolvIT is an IT outsourcing company that sets great store by following security standards. See also the 4 essentials for securing your office infrastructure.