Your From header is the main thing that people use to find out who you
are.  You can use either of the following formats for your From
header:

 From: Full Name <userid@fully.qualified.domain.name>
 From: userid@fully.qualified.domain.name (Full Name)

For example, I can use either of these:

 From: Nancy McGough <nancym@ii.com>
 From: nancym@ii.com (Nancy McGough)

The first format is preferred.

Your userid is usually your login name and can not easily be changed.  
Your fully qualified domain name (FQDN) is the domain name used by your 
Internet provider.  If you have a choice of FQDNs to use, I recommend 
using the shortest one.  For example, at one of my providers I can use 
either nancym@coho.halcyon.com or nancym@halcyon.com.  I like the second 
one because it is shorter and easier for people to type and remember.

Your full name is usually in the file /etc/passwd and is the name that
people see when they finger you.  On many systems you can change your
full name using the chfn command, which was described in section 2.2.1
above.

Some newsreaders and mailers allow you to customize your From line
using commands specific to that tool.  If you do this be aware of a
these important points:

 * Customizing your From header will not hide your identity since the
   transport agent will append a header, such as the Sender header,
   that includes your real identity.

 * In some newsreaders you will not be able to cancel an article that
   you posted using a customized From header.