I want to use the mail() function in PHP. In order to do that, I've installed postfix. I am running on Ubuntu 18.04.

My problem is that I can't send mail as I have a "connection refused" output.

In the terminal, I try :

```

    echo "This is the body of the email" | mail -s "This is the subject line" ailiganon@gmail.com

```

And I get this output in mail.log

```

    Jan 11 01:14:39 AiliganonPC postfix/pickup[9411]: 207FE16016CD: uid=0 from=<root@AiliganonPC>
    Jan 11 01:14:39 AiliganonPC postfix/cleanup[12552]: 207FE16016CD: message-id=<20220111001439.207FE16016CD@example.com>
    Jan 11 01:14:39 AiliganonPC postfix/qmgr[9412]: 207FE16016CD: from=<root@AiliganonPC>, size=370, nrcpt=1 (queue active)
    Jan 11 01:14:39 AiliganonPC postfix/smtp[12554]: connect to gmail-smtp-in.l.google.com[2a00:1450:4010:c0e::1a]:25: Network is unreachable
    Jan 11 01:14:39 AiliganonPC postfix/smtp[12554]: connect to gmail-smtp-in.l.google.com[74.125.131.27]:25: Connection refused
    Jan 11 01:14:39 AiliganonPC postfix/smtp[12554]: connect to alt1.gmail-smtp-in.l.google.com[2404:6800:4008:c13::1a]:25: Network is unreachable
    Jan 11 01:14:39 AiliganonPC postfix/smtp[12554]: connect to alt1.gmail-smtp-in.l.google.com[142.250.157.27]:25: Connection refused
    Jan 11 01:14:39 AiliganonPC postfix/smtp[12554]: connect to alt2.gmail-smtp-in.l.google.com[2607:f8b0:400e:c06::1b]:25: Network is unreachable
    Jan 11 01:14:39 AiliganonPC postfix/smtp[12554]: 207FE16016CD: to=<ailiganon@gmail.com>, relay=none, delay=0.28, delays=0.02/0.01/0.24/0, dsn=4.4.1, status=deferred (connect to alt2.gmail-smtp-in.l.google.com[2607:f8b0:400e:c06::1b]:25: Network is unreachable)

```

Also, the output of the following command:

```

    telnet alt2.gmail-smtp-in.l.google.com 25

```

is

```

    Trying 108.177.98.26...
    Trying 2607:f8b0:400e:c06::1b...
    telnet: Unable to connect to remote host: Network is unreachable

```

What I've tried :

Verify that my port 25 was opened and not blocked by firewall :

```

    sudo lsof -i:25

```

```

    COMMAND   PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
    master  12899 root   13u  IPv4 4027269      0t0  TCP *:smtp (LISTEN)
    master  12899 root   14u  IPv6 4027270      0t0  TCP *:smtp (LISTEN)

```

Disable my firewall

I've also tried with a different mail address (not on gmail) and get same output.

In /etc/postfix/main.cf, I've changed inet\_protocols from all to ipv4 and then I've pt it back to "all".

Here's the configuration of my file :

```

    smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
    myhostname = example.com
    alias_maps = hash:/etc/aliases
    alias_database = hash:/etc/aliases
    mydestination = $myhostname, ailiganonpc, AiliganonPC, localhost.localdomain, localhost
    relayhost =
    mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
    mailbox_size_limit = 0
    recipient_delimiter = +
    inet_interfaces = all
    inet_protocols = all

```