Messaging is older than the web services and in some ways easier to provide. In this section, I'm first going to look at the elder statesman of messaging services: e-mail.
Nowadays, we also use systems that send SMS textual information and we will look at two of these: Twitter and Esendex.
Sending e-mails conventionally happens on the well-known port 25, although other ports such as 465 and 587 are now more commonly used (http://www.esendex.co.uk).
This uses the Simple Mail Transport Protocol (SMTP), which was first formulated in the early 1980s and consists of formulating a message the SMTP server can understand, with fields such as To:, From:, and Subject: together with the text of the message and then deposit in the mail service's ...