Pick Spark for teams, Thunderbird for control, Mailspring for a clean desktop inbox, and eM Client for an Outlook-like feel without the Outlook mood. Spark says it has 17.5 million users, which tells you people really do want email to feel less like sorting laundry with boxing gloves on [source: Spark].
TLDR: If you answer lots of mail with other people, use Spark. If you want free, open-source power, use Thunderbird. If you want a simple app with a nice interface, try Mailspring. For example, a two-person sales team sending 80 emails a day may save time with Spark’s shared inbox tools, while a solo writer may be happier with Thunderbird and zero subscription drama.
The quick comparison
- Mailspring: Best for a clean desktop email setup.
- Spark: Best for teams and shared email work.
- Thunderbird: Best for free power and add-ons.
- eM Client: Best for users who want email, calendar, and contacts together.
1. Mailspring: pretty, simple, and a little limited
Mailspring feels friendly right away. The design is neat. The menus make sense. You can add Gmail, Outlook, Yahoo, iCloud, and other IMAP accounts.
Its best trick is the unified inbox. All accounts sit in one place. That is good if you have work email, side gig email, and that one ancient address you keep for pizza coupons.
Mailspring also offers handy features like:
- Read receipts
- Link tracking
- Email scheduling
- Contact profiles
- Fast search
The catch is… some of the good stuff sits behind Mailspring Pro. That can feel annoying if you only need one tiny feature, like snoozing emails or tracking opens.
Best for: freelancers, solo workers, and people who want email to look nice.
Not great for: big teams, heavy calendar users, or people who hate subscriptions.
2. Spark: the team player with polish
Spark is like the friend who brings labels, snacks, and a shared Google Doc to every group project. It is built for people who talk through email with other people.
You can assign emails to teammates. You can chat about an email before replying. You can share drafts. This is great for support teams, sales teams, agencies, and tiny companies that do not want every inbox to become a swamp.
Spark also has smart inbox sorting. Newsletters, private emails, and notifications can be split up. This makes the inbox feel less loud.
Useful Spark features include:
- Shared inboxes
- Email comments
- Team drafts
- Snooze
- Send later
- AI writing tools
Honestly, it feels like Spark is trying to be email and a mini project tool at the same time. That is great if you need it. It is too much if you just want to read a receipt from the dentist.
Best for: teams, client work, and shared support email.
Not great for: users who want a plain inbox with no extra buttons.
3. Thunderbird: free, strong, and a bit nerdy
Thunderbird is the old-school champion. It is free. It is open source. It runs on Windows, Mac, and Linux. It has been around for ages, and it still does the job.
The big win is control. You can shape Thunderbird with add-ons. You can add calendars, encryption tools, filters, themes, and many account types.
Thunderbird is great if you like settings. Lots of settings. So many settings that your settings may need a small chair and a cup of tea.
Its best features are:
- Free use
- Strong filters
- Add-ons
- Local folders
- Calendar support
- Good privacy control
It drives me crazy that some setup tasks still feel older than they should. Adding accounts is much better than it used to be, but fixing odd server settings can still eat 10 extra minutes if your mail host is fussy.
Best for: privacy fans, Linux users, power users, and anyone who wants free software.
Not great for: people who want everything to feel shiny on day one.
4. eM Client: the tidy all-in-one option
eM Client is the “I want Outlook, but calmer” choice. It puts email, calendar, tasks, contacts, and chat under one roof. The interface is clean. It feels more business-like than Mailspring.
It works well with Gmail, Microsoft 365, Exchange, iCloud, and standard IMAP accounts. It also supports calendar sync, which Mailspring does not make a main feature.
Nice eM Client features include:
- Built-in calendar
- Contacts and tasks
- PGP encryption
- Translation tools
- Templates
The free version has limits. Paid plans unlock more accounts and business use. That is fair, but not thrilling.
Best for: small business users, calendar lovers, and Outlook switchers.
Not great for: people who only need a basic inbox.
Which Mailspring alternative should you choose?
- Choose Mailspring if you want a clean app and simple daily email.
- Choose Spark if your team replies to customers together.
- Choose Thunderbird if you want free, flexible, private email.
- Choose eM Client if calendar and contacts matter as much as email.
Here is the simple rule. If you work alone, start with Mailspring or Thunderbird. If you work with others, try Spark. If your day lives in email and calendar blocks, test eM Client.
Email apps are personal. Some people want speed. Some want privacy. Some just want the unread count to stop yelling at them. Try two apps for one week each. The winner is the one that makes you sigh less before opening your inbox.
