I only use my ISP's mail server for sites that I cannot reach directly. One of the disadvantages of using the ISP's server is a loss of control; once the mail is delivered to the ISP you have no control over redelivery attempts (if the remote MXes are down), can't see if the mail has actually been delivered to the remote site's mail server etc. Knowing such things can be very useful when diagnosing mail problems.
Exactly my point. If remote site is down, and you know it will be down for extended period of time (say two or three weeks), you can move mails for that site to separete queue with different set of timeouts, and inform your users about that. That way, emails will be delivered once the remote site is operational again, instead of being bounced after 5 days (and annoying warinings generated after 4 hours). Something no ISP will be willing to do for you.
Another reason might be that some people might have privacy issues with their correspondence being stored on intermediate mail server they have no controll of.
These are just two examples why in some cases using ISPs mail servers for relaying is not acceptable solution.
-- Aleksandar Milivojevic <amilivojevic@xxxxxx> Pollard Banknote Limited Systems Administrator 1499 Buffalo Place Tel: (204) 474-2323 ext 276 Winnipeg, MB R3T 1L7
