Hi @viljush43 and welcome, we are so glad to have you here!
Thanks for reaching out to the HubSpot Community!
It’s great to see that you searched for similar posts before posting, thanks for that!
Actually, on this new page “Welcome to HubSpot Community Resources & Troubleshooting Tips!”, you’ll find “New user not receiving welcome email: PLEASE READ BEFORE POSTING” that might be of interest!
When looking internally, it seems that there is a global bounce on this email address (I have hidden the email address on your post for security and confidentiality reasons): This is a hard bounce for a permanent reason across three or more HubSpot accounts. Permanent bounces include unknown user and mailbox full. Global bounces are dropped from future emails across all HubSpot accounts.
So I’d recommend submitting the form at the bottom of this article to see if this can be removed.
Thanks and I hope you’ll get sorted soon!
Bérangère