What is an email client?
An email client is the software or app you use to read, send, and manage your emails.
It can be:
A program on your computer (like Outlook, Apple Mail, or Thunderbird)
A web-based service (like Gmail or Yahoo Mail in your browser)
A mobile app (like the Gmail or Outlook app)
Think of it as your “inbox”—the tool that connects you to your email account.
Why emails look different in different email clients
Emails can display differently depending on the email client. This happens with every email service provider (ESP), but it’s especially noticeable in Outlook.
Here’s why:
When you design an email—even in a drag-and-drop editor—your ESP converts it into HTML code.
Each email client reads that code and applies its own display “rules.”
Some clients ignore certain styles or render them differently.
Why Outlook is tricky
There are many versions of Outlook still in use, especially older desktop apps.
Older versions don’t always update automatically, so they interpret HTML inconsistently.
To make an email look perfect in every version would require heavy, version-specific code—which isn’t realistic.
Even platforms like MailChimp run into these same issues.
How to handle it
Use an email testing tool like Litmus to preview designs across different clients.
Send a test email from Hive (or your ESP) to a Litmus address.
Review the previews and focus on optimizing for the clients most used by your subscribers.