From there all that is needed is for Ernie
to hit "Get New Mail" and his mail client (Mail User Agent) will collect the mail using, in this instance, the
Post Office Protocol (POP3).
9.1.2 Dissecting an email address
To go into a bit more detail about the routing of email we need to look at its key component, the email address.
The simplest way to do this is to compare it to a physical address. Of course we're not going to attempt to go
into any great detail about how real world postal addressing operates but when you look at table 9.1 it is much
easier to see how the two compare. While Bert's physical location is indicated by an increasingly widening, or
narrowing depending on how you read it, geographic description, his email address uses a series of suffixes to
identify his network location.
Table 9.1 Comparing a physical address with an email address
Physical Address Email Address
Addressee Name: Bert Account Name: bert@
Address 10 Some Street,
Sydney, NSW 2000
Account Domain: bertsblog
Generic Top-Level Domain .com
Country Australia Country Code Top-Level
Domain
.au
Just as the responsibility for relaying physical mail lies with the sending parts of the various postal
mechanisms and postal workers, so to do the sending mail transfer agents handle the transfer of email.
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