Email going to spam with Hotmail

Hi there,

When someone registers on my site, they receive an activation email. This works fine with all email providers incl. hotmail / outlook.

But, the sender is [email protected] which I recently changed into [email protected].

Only hotmail is seeing these emails now as spam. changing it back to [email protected] and all is fine again.

I made these changes hard coded in my child-theme’s functions.php and I also tried the plugin WP mail SMTP. Both same result with Hotmail.
rDNS is set – SPF record has been made by hosting provider and the email address exists (as an alias).

Also, using a tester app, the emails score 8.5/10.

Does anyone have an idea how to not make the emails go to Hotmail’s spam folder?

Thanks so much!!