display :Your message has been sent successfully. but mail not sent

A success message does not automatically mean that the user received the email successfully. It just only means that the method used was able to process the request without any errors.

there might be some delay in getting emails sometime. if not, We suggest you to check if mails are sent successfully from your server.

I get this too and native function works, eg if you create a new user and tick send credentials then it sends but with your plugin no mail is send period. ??