No, it is not.
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Squelch is automated and requires a lot of unique accounts to report a person. That was originally designed for gold seller spam, but works for other spam too. A GM will then review and decide what to do next - lift the squelch or apply a penalty.
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Silence is an actual penalty applied by a GM. It is a black mark on the account and additional silences will double in duration each time you get one.
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Suspension is removal from game totally for a set period of time. This can be done for chat violations too.
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Ban means permanently closed. I realize people do tend to use ban and suspension interchangeably as common lingo.
In your case you got an email with your penalty because a GM applied it and sent you the email template. It was not automatic.
EDIT
Here is a Customer Support Forum Agent explaining it a bit as well.