I had not run into this until recently * family/comingled e-mail addresses. I was having e-mail communication from my website with the "man of the house" regarding one of my rental properties and I was asking questions and receiving responses....then I started getting the same questions again and I asked if he had gotten my last 2 e-mail responses. It ends up that while my original communications were with him, she also used the same e-mail address and started asking the same questions again.
E-mail addresses are CHEAP * ACTUALLY they are FREE * so why, why would there be the need to share an e-mail address. E-mail me with a copy going to your spouse and I can respond to all so we keep on the same page. It saves time for everyone AND everyone gets the same information.