I understand this is a reasonable request, but the only problem I can foresee with this is:
Rules Page wrote:Rule #2: No secret diplomacy
Any form of diplomatic discussion between opponents must be posted in the game chat in a language that all opponents understand. Diplomacy includes, but is not limited to: proposing truces, negotiating alliances, and coordinating attacks. Secret diplomacy can be hard to prove, but if you suspect it you should leave the players in question appropriate ratings. If you feel certain about players engaging in secret diplomacy consider reporting them in the Cheating & Abuse Reports forum by posting a new topic.
I know that most people would only use this feature if they were following the above rule, but there are some people who would use this ability to cheat (I am not saying anything about you, as I do not know you at all).