Help me understand FDQN as some of my mails are bouncing back
I am new to owning the VPS and learning alot of things, i search for for the answers on DO and came across alot of posts some made few sense and some none probably due to my lack of knowledge.
The problem I am having is after moving to DO some of my emails that I send are getting bounced back and the error I get it as following
(reason: 550 Access denied - Invalid HELO name (See RFC2821 18.104.22.168))
After googling some posts suggests I need to look into my configuration to make sure they are done right for example make sure FDQN is setup.
When I run the command hostname i see my hosting listed on terminal so i am assuming that right, when i run the command hostname -f i see the following on terminal
So here is my first question is that right? is localhost.localdomain what we are supposed to be using? if not then how do i fix it and what to i change that to?
inside my host file i see the following lines
127.0.1.1 localhost.localdomain hostname hostname
Is this setup right? what am i missing?
Any help will be really appreciated