Hello Cem, if I can afford there is a perfect AQB module to do that. I use it to welcome, and ask the member to complete his profile in order to make the valdiation of his account a priority.

Thanks Baloo this is really beneficial.

But also I am insisting to have this welcome message through messenger to start the initial contact with site administration and users.

İt's not difficult to send to messenger from code we will do it, no problem :)