I have been using discourse since many years. All these days everything seems working fine without any issue. But from few days/months we are facing the below issue.
Whenever a new user registers/signup he is not receiving any activation email?
What could be the problem? Please help us in understanding & solving this issue.
@Helical_Insight have you looked at Troubleshooting email on a new Discourse install ? It contains a lot of useful steps in troubleshooting email issues (not just new installs). You can share the information you gain from that troubleshooting guide here and people may be better able to help you.
The important part that people will need to help you is what the logs say: what do the Discourse logs say, what do the SendGrid logs say?
What steps from the troubleshooting guide did you try/double check, what were the results? Most of that guide is generic and applies to all email providers. Does other email send out from your Discourse? Is there a particular email system that is giving you issues (Gmail, Outlook?), or are all of them not receiving email? Have you checked your email at https://www.mail-tester.com/ to see if there are other issues going on?