There are three main types of email servers, based on their function in the email delivery process.
Let’s break them down clearly 👇
📨 1. SMTP Server (Outgoing Mail Server)
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Purpose: Sends emails out from your device to another mail server.
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Protocol used: SMTP — Simple Mail Transfer Protocol.
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Example addresses:
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smtp.gmail.com -
smtp.office365.com
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Software examples: Postfix, Exim, Sendmail, Microsoft Exchange.
📤 Think of it like: the post office that sends your mail out to others.
📥 2. POP3 Server (Incoming Mail Server)
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Purpose: Receives and downloads emails to your device.
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Protocol used: POP3 — Post Office Protocol version 3.
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Example addresses:
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pop.gmail.com -
pop.mail.yahoo.com
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How it works:
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Emails are downloaded from the server to your device.
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Once downloaded, they’re usually deleted from the server (unless you choose to keep a copy).
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💾 Best for: Users who check email from only one device.
🔁 3. IMAP Server (Incoming Mail Server)
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Purpose: Receives and synchronizes emails across multiple devices.
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Protocol used: IMAP — Internet Message Access Protocol.
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Example addresses:
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imap.gmail.com -
imap.mail.yahoo.com
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How it works:
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Emails stay stored on the server.
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All devices (phone, laptop, etc.) show the same synced inbox.
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🌐 Best for: Users who access email on multiple devices.
🧠 Summary Table
| Type | Direction | Protocol | Stores Emails On | Best For |
|---|---|---|---|---|
| SMTP | Outgoing | SMTP | Sender’s server | Sending emails |
| POP3 | Incoming | POP3 | Local device | Single-device users |
| IMAP | Incoming | IMAP | Mail server | Multi-device users |