Congratulations for working at an organization that's been around for at least a year. The more years, the bigger my congratulations. Organizational longevity is (mostly) a good thing.
But let's keep that between us, okay?
As the Claxon Marketing blog says: No one cares about your anniversary:
Should you celebrate milestones? Sure. But make sure you're clear on what you're really doing and why. Don't waste resources celebrating something that other people don't really care about.
Every word, every pixel, every square millimeter of paper that you spend proclaiming your anniversary is that much space not? used telling your donors how awesome they are. Which is the real job of fundraising.
How important is your organization's anniversary to donors?
It's not important. Some donors are happy to know if you've been around a long time. But the anniversary itself is a big fat nothing.
Far better to congratulate each donor on the anniversaries of her first gift to you.