Email apps and software
The best email client is the one that fits your devices and workflow
Outlook, Apple Mail, Gmail, Thunderbird and Roundcube can all work with a custom-domain mailbox. Choose according to device support, offline access, calendar needs, privacy preferences and how much setup you want to manage.
Email client versus email provider
An email provider operates the mailbox and mail servers. An email client is the app or website used to read and send messages. For example, a UKC business mailbox can be opened in Outlook, Apple Mail, Thunderbird, a compatible mobile app or Roundcube webmail.
Five popular email clients compared
| Client | Good choice for | Custom-domain mailbox | Things to consider |
|---|---|---|---|
| Microsoft Outlook | Microsoft 365 users, calendars and business workflows | Supports standard IMAP and SMTP accounts | Features differ between classic, new, web and mobile versions |
| Apple Mail | People using iPhone, iPad and Mac | Supports standard IMAP and SMTP accounts | Settings and troubleshooting differ slightly by operating system version |
| Gmail app | People who prefer Google’s mobile interface | Can add compatible external accounts | Do not confuse the Gmail address service with a separately hosted mailbox |
| Mozilla Thunderbird | A free desktop client with flexible account management | Supports standard IMAP, POP3 and SMTP | Advanced flexibility can mean more settings to understand |
| Roundcube webmail | Opening a hosted mailbox directly in a web browser | Provided with compatible UKC hosted mailboxes | Designed mainly for mail rather than a complete office suite |
Settings that matter more than the client name
Correct server name
Use the exact incoming and outgoing hostname shown for the mailbox. This helps the name match the server certificate.
Secure ports
For current UKC mail services, use IMAP 993 with SSL/TLS and SMTP 587 with STARTTLS, or SMTP 465 when implicit TLS is required.
Full username
The username is normally the complete mailbox address, not only the text before the @ symbol.
SMTP authentication
Enable authentication for outgoing mail and use the mailbox credentials. Never send the password to support.
See the complete IMAP, POP3 and SMTP port guide.
Step-by-step setup guides
Use the guide for the application and device you are configuring. Each guide explains where to enter the UKC hostname, secure ports, full username and authenticated SMTP details.
Microsoft Outlook
New and classic Outlook routes, manual IMAP settings and common sending problems.
Apple Mail on Mac
Add Other Mail Account, review server settings and use Connection Doctor.
iPhone and iPad
Current Settings path, IMAP account fields and primary SMTP server checks.
Gmail app
Add the mailbox as Other and Personal (IMAP), without moving it to Google.
Mozilla Thunderbird
Manual configuration, separate SMTP identity and saved-password checks.
Email client questions
Which email client is most popular?
Market-share figures vary by measurement source, device and whether webmail is counted as a client. Choose based on compatibility and workflow rather than assuming the largest product is automatically the best fit.
Should I use IMAP or POP3?
Use IMAP when you want folders and message state to remain synchronised across devices. POP3 is more suitable for a deliberate download-oriented workflow.
Can I use several clients with one mailbox?
Yes. IMAP is designed for multi-device access, but each app must use correct secure settings and the same mailbox credentials.
Does changing email client move my messages?
Not necessarily. With IMAP, the client displays the messages held by the mailbox service. Locally stored POP3 archives may need a separate migration or export.
Use your domain for professional email
Choose the mailbox service, then connect your preferred client
UKC business email supports standard secure mail protocols and browser-based webmail.