Some of these things I am sure you have already checked, but here are some
thoughts about troubleshooting these two diffferent issues, one related to
email and one to tasks, more or less in the order I would try them.
1) When the project was built, were the resources added properly from the
Enterprise Resource Pool using the Build Team tool? (And--to not overlook
the obvious--was the project correctly published to the server--and not
simply "saved"?) I know from firsthand experience that it is very easy,
given the complexity of the project pro and project server tools, to omit
small things that make a big difference.
2) How were your server user accounts created--from the company directory,
manually, etc.? Variations in naming of Project Server user accounts, in the
Enterprise Resource Pool account listing and in the resources' email
addresses in either place may be causing one or both of these issues. Make
sure they are consistent with each other and correct in comparison to your AD
information.
3) Check Server Settings for your email notifications to ensure that your
email server, domain name, etc. are correct.
4) Check "Global" Server Permissions in your Server Settings to see that
users all have the necessary permissions there, i.e., that nothing is
disallowed. Also check your Security Templates, Category and Group
Permissions to ensure that no accidental denial of permissions happened at
that level.
When I have seen this problem in the past with users, it typically is one of
two things: (a) error in making the assignment by the project manager or (b)
a problem with the way the user accounts were set up so that they don't mesh
with the company directory information.
Hope this helps,