What is the ssh_config equivalent to this syntax involving multiple at signs

[Garbage at gmx.de]

I tried
 
Host targethost
  User myuser at technicaluser@targethost
  Hostname jumphost

and it worked. Thanks a lot !

Unfortunately this doesn't yet solve my problems with Ansible but this is a different story.
But one problem remains: I have lots of targethosts and I would better write something like "Host *.servers", the asterisk stands for all the targethost1 through targethost9999.
But the targethost has to be part of the User setting. How can I use the wildcard ?

> so with multiple @'s, you're doing the equivalent of
> 
>  ssh jumphost -l "myuser at technicaluser@targethost"
> 
> maybe try something like
> 
> Match Host targethost
>   User myuser at technicaluser@targethost
>   Hostname jumphost