Formula to isolate part of text in a list of emails

Hello,
I have a long list of emails, most of which end in a standard .com format, but others end in a different format, e.g. .be or .ch

I'd like, in a new column, to extract the company name, i.e. everything between the "at" and the first 'dot' after the "at" (this forum won't let me post the "at" symbol, odd)
I have tried using the LEFT and RIGHT functions to try and isolate the text between the "at" and the dot, but I can't figure it out. I have also tried text to columns, but as the names are non-standard lengths I can't get that right either.
Any ideas please?