You don't need to encrypt it, just sign it - no privkey required to read a signed message, and you don't need someone else's pubkey to do so. Of course it won'

You don't need to encrypt it, just sign it - no privkey required to read a signed message, and you don't need someone else's pubkey to do so. Of course it won't help if your coworkers don't also sign things they send to you.