Where is the best site to host an email discussion list?  I want to host a discussion list (about historical research) with fewer than 50 participants, fewer than 100 messages (avg. less than 10K chars) per day, with the ability to include attachments (including jpegs, html, mp3, etc) and optional digesting.  I want to administer the discussion list via a web interface, and I want searchable archives of the discussion list via a web interface.  I want the domain name in email to be my own (either by email redirection or a sub-domain--I can configure either).  I want to pay up to $25 a month for the hosting, and I don't want advertising on messages.  I want the provider to show some evidence of being likely to survive for many years.  A list of the top 5 candidates would be a good answer.

Hi Bob,

Here's a list of 11 services that seem to satisfy your requirements. I'm 
appending links to pricing pages (when they exist). 

Cisto mailing list hosting
http://cisto.com/

ZoomList
http://www.zoomlist.com/
http://www.zoomlist.com/lists/admin.cgi?show=hostingPricing

Net Atlantic Mailing List Services
http://www.e-mailpro.com/
http://www.e-mailpro.com/prices.html

TalkList
http://www.talklist.com/
http://www.talklist.com/pricing.html

MindShare Design
http://www.mindsharedesign.com/
https://d0001.postmastergeneral.com/cgi-bin/pmg_signup.pl?
server_action=Price+List&service=w&product.x=69&product.y=6

SkyList
http://www.skylist.net
http://www.skylist.net/services/hosting/discussion.html

MailerMailer
http://www.mailermailer.com/
http://www.mailermailer.com/features/index.mlm

ListHost
http://www.listhost.net
http://www.listhost.net/services/Default.htm

Maileasy (micropayment, 1 penny per email)
http://www.maileasy.co.uk/
http://www.maileasy.co.uk/costs.html

Domeus (free, looks like they don't use advertising)
http://www.domeus.co.uk

TightCircle (free, not quite standard email list hosting, but worth a look)
http://www.tightcircle.com/

Try also looking at some sites listed under:

http://directory.google.com/Top/Computers/Internet/Mailing_Lists/Hosting_Compani
es

Some email hosting services are reviewed at:
http://www.epinions.com/webs-Web_Services-All-Community-7452741-Online_Services

There's a list of email list hosts at:

Internet Mailing List Providers
http://www.gweep.ca/~edmonds/usenet/ml-providers.html

Also, try these Google searches:

"email list" host OR hosts OR hosting
"e-mail list" host OR hosts OR hosting
e-mail OR email OR mailing list OR lists host OR hosts OR hosting

I had just spent about an hour researching the same question on Google 
personally; gale-ga's answer contains some better candidates than I had been 
able to find myself.  Well worth the cost.