Thanks everyone for this post. It helped me resolve the issue of non-delivery of contact form results to the email boxes located on an exchange server. For anyone else who may have this same problem, I'll summarize my situation and mail settings so you can avoid a few headaches down the road.
I have a joomla 1.5.14 installation using the qcontacts extension (I have deactivated the standard joomla contact plugin) on a web host for a client that uses an exchange server for their mail located on another provider. Several contacts are set up in the website with individual contact forms. In order to get the results of the contact forms for the individual contacts correctly sent to their exchange server email boxes, I set up the joomla mail settings as follows:
Mailer - SMTP Server
Mail from - firstname.lastname@example.org
From Name - anything you want this to be (ex. Site Admin)
Sendmail Path - leave this empty (not needed)
SMTP Authentication - Yes
SMTP Security - None (this may be different for your arrangement)
SMTP Port - 587 (check with your webhost on this setting. Port 25 is normal but my webhost
won't allow connections to a separate exchange server using port 25 so the exchange server had
to pick a different port for mail delivery)
SMTP username - email@example.com
SMTP password - password you set up for this web box on the exchange server
SMTP Host - ex7.exchangeserver.com (check with your exchange server for this setting. The MX and A records for your domain name will need to be changed by your website hosting company to reflect the settings of the mail exchange server. Tech support at your web host will need to set mail delivery to the exchange server settings for your mail to be delivered correctly).
These are my settings in qcontact's global configuration (go to Parameters) which successfully delivered the contact form results:
Send Results from - E-mail entered into form e-mail field
After Form Submission - Confirmation in a separate page
Session Check - Yes
Custom Reply - No
I ran into problems with no mail delivery if the last 2 settings (session check or custom reply) were overridden with different settings in the local parameter settings of the individual contact forms. When the local parameters reflected my global parameters for session check (yes) and custom reply (no), the mail got sent correctly. Otherwise, no delivery!
Hope this helps.