SMTP connection tester

It connects to your SMTP host on the given port, negotiates encryption, and authenticates with your credentials — confirming the mailbox can send.

Port 587 with STARTTLS is standard. Port 465 uses implicit SSL/TLS. Match the encryption setting to the port your provider expects.

Usually a wrong password (use an app password with 2FA), an incorrect host/port, or the provider blocking external SMTP access.

No. A connection or authentication result does not establish inbox placement. Provider acceptance, domain authentication, reputation, recipients and the actual message affect delivery.