Authenticated SMTP over TLS

How to connect
Other SMTP providers.

Connect another hosted mailbox or sending server using the settings supplied by your provider.

Connection preview. You can read this guide and save a mailbox for later. Live authorization and warm-up remain off. Do not enter real credentials while the connection form is disabled.

Before you start

  • A public SMTP server that supports authentication and TLS.
  • The hostname, port, encryption mode, username, and permitted password.
  • An address you are authorized to send from.

Step-by-step setup

  1. Find the outgoing mail settings

    Open your provider’s mail-client setup guide or control panel. Find SMTP / outgoing mail, not incoming IMAP or POP. If a reseller hosts your email, confirm the actual email platform first.

  2. Get credentials for the sending address

    Use the provider’s required password, app-specific password, or SMTP credential. Ask your administrator if SMTP access or the sender address is restricted.

  3. Choose Other provider in MailboxWarm

    Open Mailboxes → Add mailbox, choose Other provider, and enter your sending email address. Named SMTP services all use this same Other provider connection option.

  4. Enter the connection details

    When connections are enabled, enter the SMTP values listed below. Choose Test & connect. MailboxWarm checks authentication and the encrypted connection without sending a message.

Connection settings

Match these values to the fields in MailboxWarm. Keep passwords and keys private.

Connection option
Other provider
SMTP host
Public hostname supplied by your provider
Encryption / port
Provider’s TLS setting, usually STARTTLS / 587 or SSL / TLS / 465
SMTP username
Provider-supplied username; often your full email address
SMTP password
Provider-supplied SMTP or app password

SMTP sends; it does not read your inbox. This connection does not include IMAP access to your mailbox. Placement and rescue activity concern the controlled seed inboxes receiving warm-up messages. Provider-specific compatibility still needs live validation.

Check the result

In today’s preview, expect Mailbox saved for later. When connections are enabled, a successful check shows Mailbox connected, with warming still paused. A failed connection check is not proof of delivery or a reason to add the same mailbox again.

Once live warming is available, choose the mailbox’s plan and schedule before starting. Connecting alone does not begin warm-up, and your provider’s sending limits still apply.

Open setup preview

Troubleshooting

The server cannot be reached

Check the public hostname and TLS/port pair. Localhost, private-network servers, and unencrypted SMTP are not supported connection targets.

You only have an API endpoint

This path requires SMTP credentials. A provider’s HTTP API endpoint is not an SMTP hostname.

You cannot find your provider

Contact MailboxWarm with the provider name and public setup guide. Never include passwords, API keys, or verification codes.

Provider resources

Provider menus and account policies can change. Use their official documentation for the latest requirements.

    Use the SMTP setup documentation published by the company that hosts your email.

    Settings reviewed September 12, 2026 · Documentation review, not a live connection test.