If you need to send e-mail messages through an e-mail address with your personal domain, you have to make sure that the provider will provide you with usage of their SMTP server. The latter is the software which enables emails to be sent out. SMTP is an abbreviation for Simple Mail Transfer Protocol and it manages all outbound email messages from programs, webmail and contact web forms. When a message is sent out, the SMTP server checks with all the DNS servers around the world where the emails for the receiving domain name are taken care of and as soon as it acquires this data, it will connect to the remote POP/IMAP server to find out if the recipient mail box is available. In case it does, the SMTP server delivers the e-mail body and then the receiving server delivers it to the mailbox where the recipient can open it and read it. With no SMTP server on your server, you will not be able to send out emails at all.
