Gmail is asking for SMTP settings

When you add an address under Send mail as in Gmail, Gmail sometimes asks for an SMTP server, username, password and port. That happens when the address isn't part of your own Google account: Gmail wants to send that address's mail through the server that normally sends it. The details belong to the email provider that hosts the address. Distro never asks for them, and you never enter them in Distro.

Why Gmail asks

Gmail is checking that you're allowed to send as the address, and deciding how to send its mail. It's common for Gmail to ask for SMTP details when:

• you add an address that's hosted at another provider, such as Microsoft 365, Zoho, or the email that came with your web hosting or domain;
• you add any non-Gmail address to a free @gmail.com account;
• your Google Workspace admin requires outside addresses to be sent through their own servers.

It usually doesn't ask when you add an alias that belongs to your own Google Workspace user. Workspace aliases are part of the same Google account, so Gmail can send them itself. If you're adding a Workspace alias and Gmail asks for SMTP, check with your admin that the alias was added to your user in the Admin console: How to add a Google Workspace alias.

What each field means

Never guess these values, and don't rely on settings copied from forums. Use your provider's current documentation: Where to find SMTP settings from your email provider.

After you fill it in

1. Gmail tries to sign in to the SMTP server with the details you gave. If that fails, it shows an error and the address isn't added. Check the details with your provider. Some providers block SMTP sign-in by default or require an app password.
2. Gmail sends a verification email to the address. It arrives in the address's own mailbox (at the other provider). Confirm it.
3. Send a test from Gmail as the new address to make sure it works.
4. In Distro, open Outreach → Sending accounts, and add the address with Add sender then Enable.

What this means for Distro

Distro asks Gmail to send each email. For an address with SMTP settings, Gmail hands the message to the provider's SMTP server for delivery. That has three effects:

• Replies go to the other provider. They land in that provider's mailbox, which Distro can't read, so they don't appear in Distro's Inbox and don't stop the campaign's follow-ups.
• Deliverability depends on that provider's setup. The domain's SPF and DKIM must authorise that provider's server. See What is SPF and What is DKIM.
• If the provider password changes, Gmail can no longer send as that address until you update the settings in Gmail.

If you can, sending from a mailbox on Google Workspace avoids all three. Compare the options in Send cold email from your custom-domain email.

Gmail shows an SMTP error

Common causes, all on the provider side:

• wrong server name, port or security type for that provider;
• the username needs to be the full email address;
• the provider requires an app password, or has SMTP sign-in turned off for the account;
• two-step verification or a security policy at the provider blocks the sign-in.

Your provider's support is the right place to fix these. Distro can't see or test this connection.