There are several ports that can be used for sending emails through an email program, the most commonly used ports are:

1. SMTP (Simple Mail Transfer Protocol): This port (port 25) is commonly used for sending emails from a local computer to a server.
2. SMTPS (SMTP with SSL/TLS protection): This port (port 465) is often used for sending emails from a local computer to a server with SSL/TLS protection.
3. Submission (TLS-secured SMTP): This port (port 587) is commonly used for sending emails from a local computer to a TLS-secured server. (recommended)

It is wise to always use the ports that ideia internet recommends or which are in the settings of the mail server.

Keep in mind that some providers use different ports or that the ports are blocked in some networks. In addition, it is good to know that some providers only allow secure ports (such as SMTPS or submission) for sending email, in order to prevent spam.