In answer to your first question on embedded wildcards in a filter:
Currently this is not possible with the current interface for creating the rules. The Scalix server is able to do this, but would require some advanced knowledge (and a command line) to configure.
The filter created by the Server Rules Wizard interface includes an explicit wildcard at the beginning and end, but not embedded. If specificed then an embedded "*" is taken literally.
So, a filter of "@ru" would match both:
abc@ru.com
def@ru.org
but not (as you want):
xyz@something.ru
Unfortunately, the presence of the "@" is what triggers the filter to look for an internet address, so specifying a filter of ".ru" would not have the desired effect and even if it did it would be prone to a false positive as it would match:
Reindeer.Rudolph@xmas.com
On your second point, it is possible to negate the condition, when you set up the rule condition there is a pull down in which you select either "is" or "is not".
Hope that helps.
JG