To find out which SMTP server is being used, check the outgoing mail server settings in your email client or examine the email message headers. The SMTP server is typically listed as the “Outgoing Mail Server (SMTP)” in account settings, and in email headers, it appears in the “Received” lines showing the sending mail server. By reviewing these areas, you can quickly identify the SMTP server responsible for sending emails.

Now let’s explore this in detail — whether you’re troubleshooting email issues, auditing a mail system, configuring a website, or verifying email authentication.
 

What Is an SMTP Server?

SMTP (Simple Mail Transfer Protocol) is the technology responsible for sending email messages across the Internet. Whenever you send an email, your device connects to an SMTP server, which then transfers the message to the recipient’s mail server.

Common examples include:

• Gmail → smtp.gmail.com
• Outlook → smtp.office365.com
• Hosting providers → mail.yourdomain.com

For example, if you’re using Gmail, your outgoing server is usually smtp.gmail.com. If you’re using Microsoft Outlook

 

How to Find Out What SMTP Server Is Being Used? Step-by-Step Guide

Method 1: Check the SMTP Server in Email Client Settings

This is the easiest method.

In Outlook

Steps:

1. Open Outlook.
2. Run to File > Account Settings > Account Settings.
3. Select your email account.
4. Click Change.
5. Look at the Outgoing mail server (SMTP) field.

There you’ll see the SMTP server being used.

In Thunderbird

Steps:

1. Open Thunderbird.
2. Click Account Settings.
3. Scroll down to Outgoing Server (SMTP).
4. Check the Server Name column.

This shows which SMTP server your account is using.

On Mobile Devices

On Android or iPhone:

1. Open Mail settings.
2. Tap your email account.
3. Look under Outgoing Mail Server.
4. The SMTP address will be listed.

Method 2: Check the Email Header (Most Accurate Way)

If you received an email and want to know which SMTP server sent it, checking the message header is the most reliable method.

Every email includes hidden technical information called email headers. These show the path the email took across mail servers.

Read More: How to Find Out What SMTP Server Is Being Used?