> Attention! This is an invitation to a video conference to be held on 6 June 2020 at 01:40 pm.
I'm unsure whether "Attention!" is a good translation of Russian "внимание!"
"Attention!" seems too radical in an invitation letter.
This would not be probably a good question for the main site.
@CaptainBohemian It is +13°C in Yekaterinburg, with a slight drizzle and overcast skies.
Ah. It's not in the letter itself, it's the electronic letter subject line, the one you see when you receive a letter in your inbox. Then "Attention!" might be okay.