We've been happily recommending our clients to use Google Apps and this worked great. But now they changed to 10 users this is not really an option anymore for 95% of our clients. All our clients are small/midsize companies in Central America. Even paying the $9/month hosting costs to us is often difficult, so we can forget about $50/year/user email accounts. Are there any free alternatives?
By the way, all our clients really only need e-mail - most importantly POP mail. No online documents, calendar, etc. Just plain mail. Something like 25 accounts would be more than enough for almost all of them.