People are your weakest link
Social engineering is a long standing way to compromise security. Chunkhost reports today that they discovered accounts being compromised through social engineering of Sendgrid support. While the compromise did not work it was a close call. The only thing that saved the targeted customers was their implementation of 2 factor authentication.
We know many of our customers individually and personally, and are still careful about changing contact addresses and passwords. With larger customer bases, it’s vital that every person in the change follow security processes.