sendmail and virtual hosting: still a small annoying problem

[Stephane Bortzmeyer <bortzmeyer@netaktiv.com>]

I'm clearly rusty in sendmail (I now use Postfix but a customer wants to keep 
sendmail) and I have a small but annoying problem with virtual hosting. I have 
implemented:

http://www.sendmail.org/virtual-hosting.html

with a M4 configuration file as instructed above. It works fine except that 
To: fields are rewritten with the main domain, not the virtual one.

If I send a mail to bortzmeyer@foo.bar when the main domain is dot.bar and I 
have in the virtusertable:

bortzmeyer@foo.bar bortzmeyer

the mail is received with a header:

To: bortzmeyer@dot.bar

which is not what the customer wants.

Any simple solution?