Choosing the Right Email App for Your Business

Why Your Email App Matters More Than You Think

You have invested in a professional email address on your own domain. You have chosen a reliable email provider with proper security, spam filtering and synchronisation. Your email infrastructure is solid. And then you open it all in a web browser tab that is buried behind fourteen other tabs, and wonder why email feels slow, disorganised and frustrating.

The email app — the software you actually use to read, write and manage your email — is the part of the email experience you interact with every single day. Your email provider handles what happens behind the scenes: delivering messages, filtering spam, securing your domain. But the app is what you see, what you click, and what either helps or hinders your productivity for hours every working day.

Choosing the wrong app is like buying a high-performance car and fitting it with bicycle tyres. The engine is there, the capability is there, but the experience is compromised by the one component you actually touch.

For a small business, the email app affects:

• Productivity — How quickly can you find messages, compose replies, and manage your inbox? A good app saves minutes on every task. Over a week, those minutes add up to hours.
• Synchronisation — Does the app support ActiveSync, so your email, calendar, contacts and tasks stay in sync across every device? Or does it only handle email, leaving you to manage the rest separately?
• Security — Does the app support two-factor authentication? Does it encrypt your connection to the server? Can it handle encrypted emails?
• Collaboration — Can your team share calendars, check availability, and schedule meetings? Or is every appointment a separate email conversation?
• Cost — Is the app free, included with your email plan, or an additional expense?

This article compares the most common email apps available to UK small businesses, explains what each one does well and where each one falls short, and helps you make a decision that matches your actual needs — not a marketing brochure.

Three Ways to Access Business Email

Before comparing specific apps, it helps to understand the three fundamentally different ways you can access your business email. Most businesses end up using all three, but for different purposes.

Webmail — The Browser Option

Webmail means accessing your email through a web browser — Chrome, Safari, Firefox, Edge. You type in a web address, log in, and your inbox appears in the browser window. There is nothing to install, nothing to configure, and nothing to update.

Best for: Quick checks when you are away from your usual device. Shared or public computers (hotel business centres, a colleague's laptop). Travelling without your own device. Situations where you cannot install software.

Limitations: Webmail works only when you have an internet connection. It typically offers fewer features than a desktop app — no offline access, limited drag-and-drop, simpler search, and a less powerful calendar view. For occasional use it is perfectly fine. For spending three hours a day managing email, it is not ideal.

Desktop App — Where the Real Work Happens

A desktop email app is installed software on your computer — Windows or macOS. It downloads your email, stores it locally, and gives you a full-featured interface for managing messages, calendars, contacts and tasks. You can work offline, search your entire archive instantly, manage multiple email accounts side by side, and use keyboard shortcuts that make email management dramatically faster.

Best for: Daily email management. People who spend significant time in their inbox. Anyone who needs calendar integration, contact management, or task tracking alongside their email. Teams that need shared calendars and scheduling.

This is where the real work happens. If email is a meaningful part of your working day — and for most business owners it is — a desktop email app is the tool that makes the biggest difference to your productivity.

Mobile App — Email on the Move

A mobile email app on your phone or tablet keeps you connected when you are away from your desk. Push notifications alert you to new messages. Calendar appointments appear alongside your email. Contacts are available when you need to make a call.

Best for: Staying on top of messages between meetings. Checking your calendar on the move. Quick replies that cannot wait until you are back at your desk.

Limitations: Mobile apps are excellent for reading and quick replies but less practical for composing lengthy emails, managing complex folder structures, or handling large attachments. They complement your desktop app — they do not replace it.

Desktop Email Apps Compared

The desktop email app is the centrepiece of your email experience. It is where you spend the most time, manage the most data, and need the most features. Here is an honest comparison of the four most common options for UK small businesses.

eM Client — Full-Featured, Modern, Excellent Value

eM Client is a desktop email application for Windows and macOS that has grown steadily in popularity among small businesses — and for good reason. It offers a comprehensive feature set that rivals Microsoft Outlook, wrapped in a cleaner, more intuitive interface that does not require a training course to navigate.

What it does well:

• Full ActiveSync support — Email, calendar, contacts and tasks synchronise seamlessly through a single connection. This is the feature that matters most for businesses, and eM Client handles it reliably.
• Clean, modern interface — The layout is intuitive and uncluttered. New users can find their way around within minutes. Multiple themes and layout options let you customise the appearance to suit your workflow.
• Fast, powerful search — eM Client indexes your entire email archive locally, which means searches return results almost instantly. When you are looking for an email from six months ago, speed matters.
• Calendar with shared calendars — The built-in calendar supports shared calendars, meeting invitations, and availability checking. It integrates directly with your email, so you can create calendar events from email messages with a single click.
• Contact management — Contacts are integrated into the email interface. When you compose a message, contacts auto-complete. When you receive a message, the sender's contact card is a click away. Contact data synchronises with your server and all your other devices.
• Multiple accounts — You can manage several email accounts from different providers in a single window. Business email, personal email, and any other accounts all live side by side with separate inboxes or a unified view.
• Task management — Built-in tasks synchronise with your email server, so to-do items appear on all your devices.
• Auto-discovery — When you add a new account, eM Client typically detects the correct server settings automatically. You enter your email address and password, and the app does the rest. No need to look up server addresses, port numbers, or encryption settings.

Cost: eM Client offers a free version for personal use that supports up to two email accounts. The Pro version, which adds unlimited accounts and commercial licence terms, is available as a one-time purchase — not a monthly subscription. For epost.plus business email customers, eM Client Pro is included at no extra cost.

Platform: Windows and macOS.

Microsoft Outlook — Powerful but Complex

Microsoft Outlook is the industry standard in large enterprises and has been for decades. It is powerful, deeply integrated with the Microsoft ecosystem, and offers a vast feature set that covers email, calendar, contacts, tasks, notes, and more.

What it does well:

• Full ActiveSync and Exchange support — Outlook was built alongside Exchange and ActiveSync, so its synchronisation capabilities are excellent.
• Deep Microsoft 365 integration — If your business uses Word, Excel, Teams, SharePoint and OneDrive, Outlook ties them all together. Meeting invitations can include Teams links. Attachments can be shared via OneDrive. Calendar integrations with Teams are seamless.
• Advanced features — Rules, conditional formatting, categories, quick steps, search folders, delegate access, room booking — Outlook has features for almost every email management scenario imaginable.
• Enterprise pedigree — Outlook is what most large organisations use, which means it handles complex email environments, large mailboxes, and enterprise security requirements without difficulty.

Where it falls short for small businesses:

• Complexity — Outlook's feature set is designed for enterprise users with dedicated IT departments. For a sole trader or a team of five, it can feel overwhelming. Many of its features are unnecessary for a small business, yet they add to the interface complexity and the learning curve.
• Cost — Outlook is not sold as a standalone product in most cases. You need a Microsoft 365 subscription, which starts at approximately £5 per user per month for the basic plan and goes up to £10 or more for the business plans that include desktop apps. Over a year, for a team of five, that is £300 to £600 — on top of your email hosting.
• Resource usage — Outlook is known for being resource-hungry. On older machines or laptops with limited memory, it can feel sluggish. Large mailboxes compound the problem.
• Occasional quirks — Long-time Outlook users will recognise the frustrations: profile corruption, inconsistent search results, calendar invitation formatting issues, and the occasional need to rebuild the data file. These are manageable, but they require more technical confidence than other apps demand.

Cost: Part of Microsoft 365 subscription (from approximately £5/user/month). Standalone purchase options are limited.

Platform: Windows and macOS (the macOS version has historically had fewer features, though Microsoft has been closing the gap).

Mozilla Thunderbird — Free but Limited for Business

Thunderbird is a free, open-source email client developed by the Mozilla Foundation (the same organisation behind the Firefox web browser). It has a loyal user base and a long history, and it is a solid choice for personal email. For business use, however, it has significant limitations.

What it does well:

• Completely free — No purchase, no subscription, no licence fees. For individuals and very small businesses on a tight budget, this is a genuine advantage.
• Open source — The code is publicly available, which means it is transparent, regularly audited by the community, and free from vendor lock-in.
• Reliable IMAP email — For straightforward email management using IMAP, Thunderbird is dependable. It handles email well, supports multiple accounts, and includes decent search capabilities.
• Extensions — Thunderbird supports add-ons that can extend its functionality — additional calendar features, encryption tools, and interface customisations.
• Cross-platform — Thunderbird runs on Windows, macOS and Linux, making it the most platform-flexible option in this comparison.

Where it falls short for business:

• No ActiveSync support — This is the critical limitation. Thunderbird does not support ActiveSync, which means it cannot synchronise email, calendar, contacts and tasks through a single connection. You can set up IMAP for email, but calendar and contacts require separate configurations using CalDAV and CardDAV — and task sync is not available.
• Basic calendar — The built-in calendar component (formerly the Lightning add-on) is functional but basic compared to the calendar features in eM Client or Outlook. Shared calendars, availability checking, and meeting scheduling are limited.
• Basic contact management — Thunderbird's address book is functional for storing contact details but lacks the integration and smart features of more modern clients. Auto-complete is basic, and there is no rich contact card view.
• No task synchronisation — Tasks cannot be synchronised with your email server, which means to-do items created in Thunderbird stay in Thunderbird.
• Interface age — Despite recent visual updates, Thunderbird's interface still feels older and less polished than eM Client or Outlook. For businesses that value a professional, modern-looking work environment, this matters.

Cost: Free.

Platform: Windows, macOS, Linux.

Apple Mail — Simple but Limited

Apple Mail is built into macOS and iOS. On iPhones and iPads, it is one of the best mobile email experiences available. On the Mac desktop, it is a different story.

What it does well:

• Built in — no installation needed — Apple Mail comes with every Mac. There is nothing to download, install, or configure beyond adding your email account.
• Clean, simple interface — Apple Mail's design is clean and uncluttered. For users who value simplicity above all else, it is pleasant to use.
• ActiveSync on iOS — On iPhones and iPads, Apple's built-in email, calendar and contacts apps support ActiveSync natively and provide excellent synchronisation.
• Integration with macOS — Apple Mail integrates with macOS Calendar, Contacts and Reminders, providing a basic level of cohesion within the Apple ecosystem.

Where it falls short for business:

• Desktop ActiveSync is limited — While iOS Mail has full ActiveSync support, the macOS desktop version has a more limited implementation. Calendar and contact sync work through separate macOS apps, and the integration is not as seamless as a dedicated desktop client.
• No Windows version — Apple Mail only exists on Apple devices. If your business uses a mix of Macs and Windows PCs — which many small businesses do — Apple Mail cannot be your standard email app across the team.
• No task management — Apple Mail has no built-in task or to-do functionality. macOS Reminders is a separate app that does not integrate with email in a meaningful way.
• Limited multiple account management — While you can add multiple accounts, the tools for managing them side by side are more basic than eM Client or Outlook.
• Search can be inconsistent — Apple Mail's search has historically been a source of frustration, sometimes failing to find messages that are clearly in your mailbox. Recent macOS versions have improved this, but it is still not as reliable as eM Client's local index search.

Cost: Free (included with macOS and iOS).

Platform: macOS, iOS only.

Feature-by-Feature Comparison

Here is a direct comparison of the four desktop email apps across the features that matter most to UK small businesses:

What to Look for in a Business Email App

Comparing features in a table is useful, but it does not tell you which features actually matter for your specific business. Here is a practical guide to the features that make the biggest difference in daily use.

ActiveSync or Exchange Support

This is the single most important feature for a business email app. ActiveSync — think of it as a universal translator between your email server and your devices — is the protocol that synchronises your email, calendar, contacts and tasks through a single connection. Without it, you are managing multiple separate services instead of one unified system.

If your email provider supports ActiveSync (and any good business email provider should), your email app needs to support it too. Otherwise, you are paying for synchronisation capabilities you cannot use.

Calendar with Shared Calendars and Availability

A built-in calendar is useful. A calendar that supports shared calendars and availability checking is transformative. Shared calendars let team members see each other's schedules. Availability checking (sometimes called "free/busy lookup") lets you see when colleagues are free before sending a meeting invitation. Together, these features eliminate the back-and-forth email chains that waste hours every week.

If your email app does not have a built-in calendar — or if its calendar does not support sharing and availability — you are missing one of the most powerful productivity features available to small businesses.

Contact Management with Smart Search

A good email app integrates contacts directly into your workflow. When you start typing a name in the "To" field, the app should auto-complete from your synchronised contact list. When you receive a message, the sender's full contact details should be a single click away. Contact data should synchronise with your server so that changes you make in the app appear on all your other devices.

Basic contact management — a simple address book you have to open separately — is not enough for business use. You want contacts that are woven into the email experience, not bolted on as an afterthought.

Multiple Account Support

Most business owners have more than one email address. You might have your main business email, a secondary business account, a personal email, and perhaps an account from a previous role that still receives important messages. A good email app lets you manage all of these in a single window, with separate inboxes or a unified view, depending on your preference.

Security Features

Your email app should support:

• Encrypted connections — All communication between the app and your email server should be encrypted using TLS. This is standard in all modern apps, but it is worth verifying.
• Two-factor authentication compatibility — If your email provider supports two-factor authentication (and it should), your email app must be able to work with it. Some older apps struggle with modern authentication methods.
• OAuth 2.0 — Modern authentication that allows the app to connect to your email server without storing your password locally. All four apps in this comparison support OAuth where the server provides it.

Ease of Setup — Auto-Discovery

Setting up an email account in a desktop app used to require knowing your incoming server address, outgoing server address, port numbers, and encryption type. Modern apps support auto-discovery, which means you enter your email address and password, and the app figures out the rest automatically. This is particularly valuable for small businesses without dedicated IT support.

All four apps in this comparison support auto-discovery, but eM Client and Outlook tend to handle it most reliably with ActiveSync-enabled providers.

Mobile Email Apps: A Brief Overview

While the desktop app is where most email work happens, your mobile app keeps you connected between desk sessions. Here is a quick guide to the main options.

iOS Mail (iPhone and iPad)

The built-in Mail app on iOS is one of the best mobile email experiences available. It supports ActiveSync natively, which means your email, calendar, contacts and tasks synchronise seamlessly. Setup is straightforward — add your account in Settings as an "Exchange" account and everything connects automatically. For most business users, the built-in iOS apps (Mail, Calendar, Contacts) are all you need on your iPhone.

Outlook Mobile (iOS and Android)

Microsoft Outlook is available as a free app on both iOS and Android. It provides a clean, focused inbox with calendar integration and supports ActiveSync connections. If you are an Outlook user on the desktop, the mobile app provides a familiar experience. It also works well with non-Microsoft email providers.

Android Default Mail and Calendar

Most Android devices include built-in email and calendar apps that support ActiveSync. Samsung devices, Google Pixel phones, and others all handle ActiveSync connections well. Setup typically involves adding your account as an "Exchange" or "Corporate" account. The experience varies slightly between manufacturers, but ActiveSync support is reliable across the board.

Gmail App (iOS and Android)

The Gmail app can connect to non-Gmail email accounts, but it uses IMAP only — not ActiveSync. This means you get email synchronisation but not calendar, contact or task sync through the app. For a business email account with ActiveSync support, the Gmail app is not the best choice. Use the built-in Mail app or Outlook mobile instead, and get the full synchronisation experience.

The Verdict: Which App Is Right for Your Business?

After comparing features, costs, platforms and real-world usability, here is the straightforward advice for UK small businesses.

If You Need the Best Balance of Features, Simplicity and Value

eM Client is the strongest choice for most UK small businesses. It provides full ActiveSync support, an integrated calendar with shared calendars and availability, comprehensive contact management, task sync, fast search, and a clean modern interface. It runs on both Windows and macOS. The free version is genuinely useful for sole traders, and the Pro version is a one-time purchase — not an ongoing subscription that adds to your monthly overheads.

For businesses using epost.plus, the decision is even simpler: eM Client Pro is included with every business email plan at no additional cost.

If You Are Already in the Microsoft Ecosystem

Microsoft Outlook makes sense if your business already uses Microsoft 365 for Word, Excel, Teams and SharePoint. The integration between Outlook and the rest of the Microsoft suite is genuinely valuable. But if you are not already paying for Microsoft 365, adding a subscription purely for Outlook is expensive — especially when eM Client provides equivalent email, calendar and contact features at a fraction of the cost (or included with your email plan).

If Budget Is Your Primary Concern

Thunderbird is free and handles basic email well. But "free" comes with significant limitations for business use: no ActiveSync, no proper calendar sync, no contact sync across devices, and no task management. If you are a sole trader who only uses email on a single device and does not need calendar or contact synchronisation, Thunderbird may be adequate. For any business that uses multiple devices or has more than one person, it is a false economy.

If You Are an Apple-Only Business

Apple Mail is built in and works well enough if every person in your business uses a Mac and an iPhone exclusively. But its desktop ActiveSync support is limited, it has no Windows version, and it lacks task management. If you are an Apple-only shop, eM Client for macOS gives you a significantly better experience while still being part of the Apple ecosystem.

How epost.plus and eM Client Work Together

The combination of epost.plus email hosting and eM Client as the desktop application creates a complete, integrated email experience that works seamlessly across every platform.

On Your Desktop (Windows or macOS)

eM Client connects to your epost.plus mailbox via ActiveSync. You enter your email address and password, eM Client auto-discovers the server settings, and within moments your email, calendar, contacts and tasks are all synchronised. The interface is clean, the search is fast, and everything works together in a single, unified application.

On Your Phone (iPhone or Android)

Your phone's built-in mail, calendar and contacts apps connect to epost.plus via ActiveSync. Setup takes two minutes. Push email delivers messages instantly. Calendar events, contacts and tasks synchronise in real time. If you lose your phone, your administrator can remotely wipe business data.

In Your Browser (Anywhere)

When you need to check email from a device where you cannot install software, epost.plus webmail gives you full access to your inbox, calendar, contacts and tasks through any web browser. The webmail interface is powered by Axigen and provides a responsive, modern experience.

Everything Stays in Sync

Read an email in eM Client on your laptop — it appears as read on your phone. Accept a meeting on your iPhone — it shows on your laptop and your webmail. Save a contact on your Android phone — it is available in eM Client within seconds. There is one source of truth — your epost.plus mailbox — and every device shows the same, up-to-date information.

This is what "integrated email" actually means in practice: not a collection of separate tools that you hope will stay roughly aligned, but a single system where email, calendar, contacts and tasks work together across every device you own.

Security Across Every Platform

Whichever app or device you use, your epost.plus email is protected by the complete email authentication stack:

• SPF, DKIM and DMARC at the strongest levels (DMARC at p=reject with strict alignment) — protecting your domain from impersonation
• MTA-STS in enforce mode — ensuring all connections to your mail server are encrypted
• DANE with certificate pinning — preventing man-in-the-middle attacks on email delivery
• DNSSEC — protecting your domain settings from tampering
• Free SSL encryption — all connections between your devices and the server are encrypted

This security applies regardless of which app you use to access your email. Whether you are in eM Client, iOS Mail, Android Mail, Outlook, or webmail, your communications are protected by the same enterprise-grade infrastructure.

Business email plans with eM Client included are available through smartxhosting.uk. For a detailed side-by-side comparison of email apps, visit the email client comparison page.

Frequently Asked Questions

See Also

• Email, Calendar and Contacts in Sync: Why It Matters
• How to Choose the Right Email Provider for Your UK Business
• Setting Up Professional Email for a New UK Business