If a couple have children, their relationship doesn't end when they get divorced. They will continue to interact for the rest of their combined lives. The worst way to communicate is in front of the children. Parents who communicate in person tend to do so when they exchange the children for visitation. The children are exposed to every argument and every angry word. Children pick up on these and are likely to have adverse reactions. Even if the children don't show a reaction, they are likely to suffer emotionally. If the parents communicate by telephone, children are likely to hear one side of the conversations. It is better to keep the communications entirely private from the children. E-mail does this.
Email offers many advantages to other forms of communication. E-mail is private. It allows a greater ability to think before responding. A person who is prone to spontaneous statements can reflect before writing a response. Email can be printed and produced in court. This provides a protection against a party who is unreasonable when negotiating but denies it in court. The ability to produce Emails in court also provides a protection against swearing and threats. With E-mails, the parties can discuss the children without exposing the children to the conversations and still make the necessary arrangements.
If the parties improve their communications, they are likely to avoid problems that will cause them to return to court.