Great news, up until yesterday the sender email of Wix Forum notifications was notifications@forums.wix.com.
From now on the sender name will be the name you choose to your forum.
In order to change it, head to the Editor, go to your Forum page, open the Forum Settings and change you Forum name under the 'Categories' tab.
You can see that notifications you're getting from this Forum now under the sender name of 'Feedback Forum'.

Please note, the email sender URL is still notifications@forums.wix.com.
This is amazing news, however, i cannot wait to see if we can get the sender URL changed. ;)
one more step, it's better but missing private message
When will we be able to change the sender URL?
When i ll be able to send notification from my own email address
This is great news, however it would be nice to customize the sender URL, especially for those of us running our Wix sites with premium plans. Although I think this is a great improvement, having a customizable sender URL would give sites a more professional look and feel. It is great to see new updates rolling in at a consistent rate, and I hope to see more improvements soon!
- Survival Gaming