[imp] No domain name for default identities

[Jaap Winius]

Hi folks,

The other day I set up a new system based on Horde 3.3.9 and IMP  
4.3.8. Well, actually I'm guilty of taking a shortcut and copying the  
entire horde directory structure from another system that already  
worked. I installed a new empty Horde database for it using the same  
passwords as on the other system and -- Presto! -- it worked.

Well, there is one problem. When users login to this new Horde setup  
for the first time, they can't send any mail. The problem is that the  
domain name is absent. For instance, my default identity is: jwinius@

When I try to compose and send a message anyhow, I get this Horde/IMP error:

    Validation failed for: jwinius@ Your From address is not a valid email
    address. This can be fixed in your Personal Information options page.

Of course, I can always change the default identity so that it will  
work, but I'd rather not have to do that for every single new user.

Any idea how to fix this problem?

Thanks,

Jaap