Whenever I see a red lock icon in gmail, I thought the sender doesn't have SSL configured.
But one person told me only server (gmail in our case) SSL is enough?
Does that mean the sender don't need to configure any SSL at all and can communicate with gmail over SSL since gmail already supports it? Or both party need SSL to communicate in SMTP?
If one party SMTP SSL is enough why do some companies still deliver the message as plain text?