I need information about any company/website that provide newsletter
service that I can use to promote a software product.

For example, I have found this :

http://www.neatnettricks.com/
http://www.infopackets.com/
http://www.lockergnome.com/
http://www.langa.com/

But I do NOT want any information about mass mailing service, for example,
a company which sell email addresses, or rent email addresses.

And also I do NOT want any information about newsletter service that
will charge me based on CPM (cost per 1000 impressions). For example,
their newsletter has 100000 users, and their CPM cost is $100. Then if
I want my advertisement for all the users, I must may $100 x 100 CPM =
$10,000 USD.
For example: http://www.pcmagmedia.com/online/newsletters.html
I do NOT want that kind of information.

In other words, I would like to find "popular" online newsletters
which has quite big users, specifically about IT and software. Because
I want to place an advertisement for my software product.

Thank you,

Regards,
AU

One of the biggest of which I'm aware, with a reasonable price (or at
least they used to be) is Woody's Office Watch:

http://www.woodyswatch.com/

If your product is Office related, I'll post it on my site for free,
but I don't have a big subscription base yet:
www.vbaexpress.com/cooltools.htm

You might also want to hook up with JupiterMedia, who owns *half the
tech sites* (figure of speech) on the net:
http://e-newsletters.internet.com/

My answers are free. :)
I hope they help!