Do you use acronyms when speaking to someone whom you KNOW won't know what it means?

I'm new at work.
It is so annoying to me

To receive and email saying 'meeting at 10am in the DCB building'. You know I've been been there

So why not tell me wtf and where TF that is
💁

Or
' log on to ECO'
again, what IS that?

Tell someone the full name before you start using acrynyms and abbreviations. I find this so annoying