title: using ip adress with postfix instead of domain name
body: <p>what I am trying to do is (only) send a verficstion email to anyone who has signed up on my website I have written the php code and it's very simple</p>
  <pre><code>$to      = '//my email address for testing ex:user@gmail.com';
  $subject = 'Signup | Verification';
  $message = '
  //email body
  ';          
  $headers = '&lt;From:noreply@[//my Ip address]' . &quot;\r\n&quot;;
  mail($to, $subject, $message, $headers);
  var_dump(mail($to, $subject, $message, $headers));
  </code></pre>
  <p>This returns bool(true) (as it's supposed to) but the problem is that the email isn't received on gmail.</p>
  <p>so I looked into my mail.log (located in /var/log/mail.log) since mail.err is empty I get this error:
  connect to gmail-smtp-in.l.google.com[108.177.127.27]:25: Connection timed out
  and same with added alt1/2/3/4 in front of gmail-smtp-in.l.google.com ex:alt1.gmail-smtp-in.l.google.com</p>
  <p>this is my current main.cf for postfix :</p>
  <pre><code># See /usr/share/postfix/main.cf.dist for a commented, more complete version
  
  
  # Debian specific:  Specifying a file name will cause the first
  # line of that file to be used as the name.  The Debian default
  # is /etc/mailname.
  #myorigin = /etc/mailname
  
  smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
  biff = no
  
  # appending .domain is the MUA's job.
  append_dot_mydomain = no
  
  # Uncomment the next line to generate &quot;delayed mail&quot; warnings
  #delay_warning_time = 4h
  
  readme_directory = no
  
  # See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
  # fresh installs.
  compatibility_level = 2
  
  
  
  # TLS parameters
  smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
  smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
  smtp_tls_security_level = may
  
  smtp_tls_CApath=/etc/ssl/certs
  smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
  
  
  smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
  myhostname = localdomain 
  #this (localdomain) is set in /etc/hosts to my ip adress
  #most of the stuff is set to defualt values such as tls things
  alias_maps = hash:/etc/aliases
  alias_database = hash:/etc/aliases
  myorigin = /etc/mailname
  mydestination = $myhostname, pop-os.localdomain, localhost.localdomain, localhost
  
  
  smtp_sasl_auth_enable = yes
  smtp_sasl_password_maps = static:USERNAME:PASSWORD
  smtp_sasl_security_options = noanonymous 
  
  
  relayhost = 
  
  mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
  mailbox_size_limit = 0
  recipient_delimiter = +
  inet_interfaces = loopback-only
  inet_protocols = ipv4
  </code></pre>
  <p>should this be on server fault instead? do I delete this and post it there or just post it there?</p>