Work out differing views in professional relations ideally in person or at least on the phone. E-mail is not a suitable communication channel because it causes confusion and does not protect privacy.
Do not have to have the last word
Saying something unnecessarily just to have the last word will backfire on you. You certainly know this from your personal life.
Remind yourself that less is often more
Most questions can be answered quickly and easily. The people you work with will appreciate it when you talk briefly. Additionally, they will see it as polite.
Keep some opinions to yourself
Before expressing your opinion, consider whether it will not harm anyone - including yourself and the company. A more diplomatic approach is needed.
Do not be afraid of silence
An awkward silence often occurs in negotiations. You should, however, follow the rule of not speaking first. You have already said what you wanted to say. Now, remain self-confident and wait for a response. The person who speaks first after a moment of silence usually loses the argument.
-kk-