What is considered spamming chat exactly?

As a player that spends a lot of time in this game on trading, I've been warned by support 2 times withing last 10 days for spamming chat. (I mean I got a message from xxxGGG in yellow color.)
What is considered a spam?
Becuase as far as I know, my actions cannot be considered spam.
What I am doing is jumping on trade channels 1-30, pasting my trade offer once every time.

So:
/trade 1
WTB XXX
/trade 2
WTB XXX
/trade 3
.... etc.

My thinking is that, if you are regular player that sits on 1 trade chat, it can never be seen as spamming as you see only one of my message.
As trader who does the same you dont even care what is typed in trade chat as you are there only to advertise your offer and you are gone half a second after.

Should I stop my actions in the way I have been doing it, or should I simply ignore messages from support I'm receiving?
Should I answer messages from support?
Thanks for answer.

so you post 30 messages across the channels, how often?

Also could be considered spam if you have included non trade channels.

But basically, almost every chat warning or mute comes from reports made by players, GGG don't have enough staff to constantly sit and monitor every chat channel and it is very rare that they will see themselves an infraction.

Your choice in what to do, but if you've been warned you'll then get muted if you continue the mutes double in duration.