Gmail UI does not show properly formatted email signatures

Today I learned something really annoying. A person wanting to see an item I am trying to sell asked me to contact her by email so that she could come and see the item. I sent an email to her gmail address saying my contact information is below in the signature.

She replied that she cannot find my contact information anywhere. I replied that the contact information was already in the message she replied to and to make sure I copied the information to message text.

The nasty lesson is this: Gmail user does not show properly formatted email signatures to user by default. User has to click on a button with three dots on it, onmouseover-text saying "Show trimmed content" in order to see the signature containing contact information.

An email signature is the few lines of contact information that is attached to the end of every email message. Actually there is a technical definition for a signature in RFC 3676. The need for giving a specification about what a correct signature should be like originates from times when Internet was used in text terminal window that had 80 characters per line. That is the reason why a specification was needed: otherwise the messages would not have been readable in some cases like message containing lines longer than 80 characters. More information about signatures can be found in Wikipedia article about signature block.

Among many other still valid things there is something really handy and important in RFC 3676. That is how signature is marked so that email programs can tell what part of the message is actual message text and what is the signature. This information is needed when replying to email messages. Most of us like that the signature of the original sender is not included when we start replying to a messages.

The correct way of showing this is to begin the signature with

--

That is "dash dash space".

This magical sequence of characters tells the properly designed email programs: "this is where the signature starts". As this functionality is defined in a RFC document one might assume that it is widely accepted and in use. I know that Microsoft has not followed this RFC for ages. I am so used to the MS tradition of making non-standard, crappy software that I am not going to concentrate on that.

I was surpised that even Google has done something as stupid as not showing the signature by default. Shame on you! Fix it ASAP!

I of course do know that majority of email users do not know anything about RFC:s or signatures and thus do not follow that. What I do not understand is why Google has deliberately chosen not to show signatures which are a part of the message. This means that Gmail user interface does not follow RFC and causes trouble to users and communication errors.