Your settings appear to be correct.
The system settings appear to be correct... except perhaps this:
Use Mailqueue System {Set to YES}
When enabled, subscription emails generated by your site will be processed in batches to lessen the load on your server. Account activation, lost passwords and other vital emails are sent instantly regardless of this setting. If your site has low traffic, subscription emails may be delayed.
If you have a large site, you may wish to enable locking. This prevents a rare situation where the same email is sent multiple times.
Also there is this option...
Enable "-f" Parameter {Set to NO}
Some sendmail servers may require the "-f" parameter to be sent with email calls from PHP. If you are having problems with users not receiving email, try enabling this option. In all likelihood, your problem will not be caused by this setting.
See what happens as time passes. If necessary, I suppose we can use the "-f" parameter but I do not know the ramifications of it.