Which system sends the mail? Mailchimp or Joomla?

joomlamailer version: 1.7.2
Joomla! version: 1.5.23
PHP version: 5.2
MySQL version: Yep!

On your page re. MailChimp STS Plugin, you say, "Regular email delivery with Joomla! via SMTP or Sendmail." Does Joomlamailer use the webhosting server to send emails to the mailing list?
With shared hosting accounts like Hostgater, sending emails is limiited - e.g. to 500 per hour, so lists over 500 would have to be throttled if that is the case.... Or does Joomlamailer somehow transfer it over to Mailchimp to be sent?

Thanks a lot.

John

Looking for an answer to this again, since I just tried to send from within Joomla! (1.5.23) and got the error "Connection was reset" - well, um, which connection? Between my browser and the admin area, or the site and php mailer, or Joomlamailer and Mailchimp, or am I not even asking the right questions....?
Appreciate any guidance.
John

I'm assuming now the whole deal gets transferred to mailchimp to send, since I just tried to send again, and it was gone in about 1.5.23 seconds! Hmmmm..... a definite answer would still be good though, 'cos I'm just thinking out loud right now!
Cheers

John