I registered using a hotmail email address. I didn't receive the activation email at first. Later when I added @sentora.io in the safe senders list then only I received activation email after requesting.
Hotmail is blocking the emails from Sentora.
@bobby told you don't use server to spam

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Sir who is Bobby ? Users should be notified to add the email or domain in their safe sender's list because I waited and waited and tried several times. Got this tips to add @sentora.io from google search. It was a pain for sometime.
I've posted your issue to the staff room, hopefully we'll get something sorted for it shortly
The Bobby reply was a joke

LOL
Bobby is the project owner/lead developer...