Server authentication means that, when an email is sent, the SMTP server checks whether the sender is really authorized. This is a critical security step to prevent spam and forged email.
🔐 What is Server Authentication?
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When the email client (Outlook, Thunderbird, etc.) or app connects to the SMTP server, it authenticates with a user name and password.
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In the settings this usually appears as “SMTP authentication” or “My server requires authentication”.
⚙️ Where Is It Set?
Outlook example:
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File > Account Settings > Email tab
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Select the account > Change > More Settings > Outgoing Server tab
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Tick the “My outgoing server (SMTP) requires authentication” box
Thunderbird example:
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Settings > Account Settings > Outgoing Server (SMTP)
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Select the server > Edit
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“Normal password” should be selected under “Authentication method”
📌 Things to Keep in Mind
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If SMTP authentication is not enabled, your emails may not be sent or may be marked as spam.
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The user name is usually your full email address (for example:
user@yourdomain.com) -
The password is your email account password, or in some cases an app password (for example in Gmail if two-step verification is enabled)
