Many "solutions" for adding signatures don't work out of the box, they're complicated and have weird configuration. They're only workarounds for a real problem. Solution is simple - use software designed for adding disclaimers and signatures to any type of messages.
- What you cannot do with common tools on the market:
- skip adding another disclaimer if already present in the message
- add different disclaimer per domain or group
- set time range to use different disclaimer on the vacation and Christmas
- and so on...