Are you setting alerts  for other people? If so, then the problem is
probably that those users  have never logged into SharePoint. SharePoint
maintains user info in two different places. First, profile information is
normally imported from Active Directory. Second, users can also be added by
giving them security permissions or by adding groups that they are a member
of to SharePoint. The profile information is only used for Profiles and has
nothing to do with either security or Alerts. The emails  for users used in
Alerts is pulled from their security record in the user and groups table.
If a user is given access to SharePoint because they are a member of an AD
group that has permissions in SharePoint then the system won't actually
track them until they log in for the first time and they won't show as a
user of the system until they have uploaded a file or created a new list
item. If they haven't at least logged in than the alert system can't access
their email address and you will get the error  referenced in your message.
Note, for alerts they only need to log in. To be viewable as a user in the
user and groups table they also need to collaborate on the site.

Is there any way to get the Profiles information into the User table? Does
anyone make a product to do that?

Things in the profiles  are automatically replicated to the User table for
any user that exists in the user table. But I don't know of any way to
populate the user table with new users  based on what has been brought into
Profiles. In general its not really necessary. The specific example of
alerts is one of the few times I've actually seen it cause a problem and in
that case you need to consider that alerts  are designed to be
self-administered. Prior to SharePoint 2007 there wasn't even a way to add
an alert for someone else using the built-in capabilities.

I have a department SharePoint application and they wanted everyone in their
department imported into SharePoint, so we set  up a Profile import.
Not everyone in the department logs into SharePoint, but the department wants
SharePoint users  to be able to get the imported information on anyone in the
department.
So there is no way to get that information, automatically, to the user table.
Is there an alternative, other than populating a list manually?

The imported information will be available when people search, because that
is searching information stored in the profile. User's don't need to login
for things like their phone number or email address to be searchable from
their Imported Profiles. But the original question dealt with setting an
alert for another user. To do that the user has to have access to
SharePoint, not just a Profile. Based on the way SharePoint works, if you
try to create a profile for another user (something that should normally be
done only by admin personnel) then it will only work IF the user has logged
into SharePoint at least once.

To summarize: Profiles store information about a user. That information is
indexed and searchable. User information is stored elsewhere in SharePoint
to support the security system. SharePoint only tracks users  who use
SharePoint in the security system. In general that information is not
searchable or usable by anyone but administrators. The People and Groups
list is the one exception to that, but in that list you will only see people
who are using the system and people who have been given individual security
rights. You won't see people who are members of groups that have rights
unless they've actually logged in. In most cases this design isn't a
problem.

This is really good information, and helps clarify a great deal - thanks, Paul.
So Is there a way, beside Search, to get a list of the a list of users  who were
imported and their profile information?

Nothing out of the box that I know of. There is a Free Web part that I've
seen, but haven't used, that is supposed to show a list of user Profiles
configured the way you want to see them. You can read about it here:

http://roxority.com/peoplezen/

Yea, I found that, but one would think that there would be more out there.

Well, if you have a human resources DB, you could set  up user profile
imports through Shared Services.

Active Directory imports work even better if you have them...

Is there a way to force the update of the user table. I have some users
that do not have valid  email addresses  in the user table, but the profiles  are
correct.

The user has logged in. I can see them in the Select People
and Groups dialog, but unlike other users, this one user has no email set. So I
can create the alert, but they are not receiving any of them. Any suggestions?

"Yea, I found that, but one would think that there would be more out there."

Hi Nisha, Phil from ROXORITY here. If you need PeopleZen to do something it can't currently do, just get in touch!