This article shows you Mille and one way to send an email (ie known as transport in SMTP.
Sending an email is also known as submitting an email to the server and the connection ports are known as submission port.
Before continuing, you need to know the basics of email and how it works with SMTP. If you don't check this page: How does the email system work? SMTP, POP, IMAP explained.
This is an advanced mechanism where you need to know the SMTP protocol. For an example, see the transaction page: How to send an email at the command line with SMTP? Email transaction explained
A user can send an email with a client application (known also as MUA)
Using a dedicated email service provider is the most easy and secure way to send email
See:
You should not send professional emails using your personal Yahoo, Gmail, Outlook, AOL, etc. in the FROM address. The emails might:
It's still possible to use the SMTP with a MTA configuration. See for instance postfix SASL solution but I don't known the repercussion. You should test it.
On a dedicated server, you may send:
It's free to send with your own host but you need to configure it properly. See How to configure your server to send Email properly?