How you can actually go about testing your email
promotions to ensure that every message you
send in bringing in the highest profits.
First of all , let's examine a couple of steps
you'll need to take before you start the testing
process:
1.Choosing your "control"
2.Deciding how many test to ran

1. Choosing your "control"

In order to get accurate results when you're testing
effectiveness of your promotions (or anything else,
for that matter) , you must test only one element
at a time. If you try testing several different element
at same time , you'll have no way to determine
which change improved your response.

For example , let's suppose you decide to test two
different e-mail promotions. The firs in structured
as a long, formal letter to your customers written
in HTML, with the subject line, "Dale could you
give me your opinion? "The second e-mail is short,
punchy note written in personal tone and delivered
in plain text, with the subject line, "Dale, could
you help me out?"

After testing both letters the small list of your
customers, you discover that the second test is
bringing in a better results, so you decide to
launch that letter to your entire list. The problem is
that you haven't learned WHY the second letter was
more successfull. Was it the subject line? The text
format...

This is why it is so important to establish a
"control" letter, and the test different versions
of your control letter with only one things change
at a time

2. Deciding how many test to run.

You can run as many test as you feel are necessary
to tweak and perfect your email promotion.
Recommendation -run a minimum of three tests
before launching their e-mail promotions.

In general, you will want to test at least two
different letters and two different subject lines
for any e-mail promotion you plan
on sending. The testing setup would look something
like this:

- Letter 1 with subject line 1
- Letter 2 with subject line 1
- Letter 1 with subject line 2

By running these three test, you will be able
to get a good feel for which elements of your
e-mail promotions are generating the best results,
so that you can launch the most profitable
combination of letter and subject line.
The more testing you do, the more targeted and
effective your promotion will be.

However, if your opt-in list contain less than a
few thousands subscribers, you may need to watch
trends over a period of a few months before you'll
have a solid feel for what your subscribers prefer
in terms of promotion stiles, format and voice.