That’s Merry Christmas and a Happy New Year to you! Rutsch means ‘slide’ so it’s really: have a good slide into the New Year. It’s winter after all and ice can make things slippery! Germans are more friendly around Christmas time and there are many traditions, not to mention much entertainment and merriment to be had around the Adventszeit (advent): from Weihnachtsmärkte (Christmas markets) to lots of performances of Humperdinck’s Hänsel und Gretel.
I used to send a simple ‘Season’s Greetings’ card to agents and theater people I had contact with featuring the above-mentioned German phrase. I used email, but these days other methods may be preferred. It’s all just to remind them of your presence and it was surprisingly often positively received. If you’ve worked with people or had legitimate contact with them it can’t hurt. If you know them well enough, a little bit of personalization can go a long way, too.