How can I make sure that a segment is not added to the translation memory?

Dear All,

I have been hired for an English to Bulgarian translation project but the client keeps sending me .xliff files in which part of the content is in Russian. Naturally, I do not want any Russian content imported into my English to Bulgarian translation memory. And as a matter of fact, the client does not even want those segments in Russian translated in the first place.

So, how should I mark those unwanted segments to make sure that they are not imported into my TMs? Just leave untranslated? Leave untranslated and then lock them? Mark them as rejected? Please, advise.

Kind regards,

Pavel