I have been copied in one lengthy email last week from unknown sender. I thought it is spam email, so I waste no time flagging it as spam. But  I found out when I check the spam folder later, other recipients in the email start replying to each other and it become quite long threaded email. So what’s going on??Why am I copied in this email??

It appears that the email was incorrectly addressed to me. The reason is the dots (.) in the email address.

Apparently Gmail doesn’t recognized dots as character in your email address. It’s quite funny considering that dots is widely used in corporate email address. Here is Gmail explanation on this when I click the ‘learn more’ button.

Gmail doesn’t recognize dots as characters within usernames, you can add or remove the dots from a Gmail address without changing the actual destination address; they’ll all go to your inbox, and only yours. In short:

• homerjsimpson@gmail.com = hom.er.j.sim.ps.on@gmail.com
• homerjsimpson@gmail.com = HOMERJSIMPSON@gmail.com
• homerjsimpson@gmail.com = Homer.J.Simpson@gmail.com