SMTP Settings: What They Are and How to Find Yours

SMTP settings are the handful of details an email app needs to send mail on your behalf: which server to hand the message to, which port to use, and how to prove you’re allowed. Get them right once and your app sends fine. Get them slightly wrong and nothing goes out, usually with an unhelpful error. This is the plain-English version.

What SMTP actually is

SMTP stands for Simple Mail Transfer Protocol. It’s the standard email clients and servers use to send mail. Its counterparts, IMAP and POP, handle receiving mail. So when you set up an email account in an app, you’ll often enter SMTP settings for outgoing mail and IMAP settings for incoming.

To send via SMTP, an app needs four pieces of information:

1. The SMTP server address, for example smtp.gmail.com or smtp.office365.com.
2. The port, usually 587 or 465.
3. Your username, almost always your full email address.
4. Your password or token, increasingly an app password or an OAuth sign-in rather than your normal password.

The ports, and which to use

The port tells the server how the connection should be secured. Three come up:

• Port 587 (STARTTLS): the modern standard for sending authenticated mail. The connection starts plain and upgrades to encrypted. Use this unless you have a reason not to.
• Port 465 (implicit SSL/TLS): encrypted from the first byte. Still widely supported and a fine choice.
• Port 25: the original SMTP port, now used mostly server-to-server. Most providers and networks block it for normal sending because spammers abused it. Avoid it.

Authentication has changed

The big shift over the last few years is that providers have stopped accepting your ordinary account password over SMTP, because it’s a security weak point. Two replacements are now normal:

• App passwords: a one-off, app-specific password you generate in your account’s security settings, used instead of your main password. Gmail requires this when two-step verification is on.
• OAuth 2.0: you sign in through the provider’s own login screen and grant the app permission, so no password is stored at all. Microsoft is moving SMTP firmly in this direction through 2026.

Which one you need depends on your provider and account type, which is exactly why the specifics live on the per-provider guides.

Find your provider’s settings

The values differ by provider, so grab the right guide:

• Gmail SMTP settings for @gmail.com and Google Workspace, including app passwords and OAuth.
• Outlook SMTP settings for Outlook.com and Microsoft 365, including the 2026 basic-auth changes.

When SMTP isn’t the right tool

SMTP settings are what you enter to send from one mailbox through an app. That’s perfect for a single account. But for cold outreach at volume, sending everything through one SMTP connection concentrates all your sending on one mailbox, which damages its reputation fast.

That’s where dedicated cold email software comes in. HotHawk connects your Google and Microsoft inboxes (over OAuth, so no fragile passwords), warms them up on real inboxes, and uses inbox rotation to spread sending across all of them automatically. You get the volume without leaning on a single SMTP connection, and every reply arrives in one Master Inbox.

A few common questions

What are SMTP settings? They’re the details an email app needs to send mail: the SMTP server address, the port, your username (your email address), and your password or an OAuth token. Together they tell the app where to send and how to authenticate.

What is the difference between SMTP and IMAP? SMTP sends email; IMAP receives it. When you set up an account in an app you often enter both: SMTP for outgoing mail and IMAP for incoming.

Which SMTP port should I use? Port 587 with STARTTLS is the modern default. Port 465 with implicit SSL also works. Avoid port 25, which is legacy and usually blocked.

Why won’t my SMTP settings work? Most often it’s the wrong port (try 587, then 465) or using your normal password where an app password or OAuth is now required. Check those two before anything else.