Postfix emails error, loops back to myself

I'm struggling with Postfix to send out emails from a form on my website:

Google Domain, hosting provided by DigitalOcean with a LAMP droplet; this is my DNS config:

Mail function on my .php file wants to send an email from: [email protected] to: [email protected]

all goes succesfully except emails are not actually sent.

/var/log/mail.log mentions that status=bounced (mail for mydomain.io loops back to myself)

Here's my main.cf config:

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 "delayed mail" 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
smtpd_tls_security_level=may

smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level=may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache


smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = packer-611a9b0e-18c5-2e19-5583-bed9efc126b7
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = 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
myorigin = /etc/mailname

I looked every guide available to tweak /etc/postfix/main.cf but nothing works, thanks in advance to anybody who's willing to help.

Unless you have MX DNS records defined, the mail to mydomain.io will be delivered to an IP from A DNS record for mydomain.io, which (as I can guess) is the same as your web application. As your application is attempting to send an email to mydomain.io through postfix it loops back to itself. You need to configure your postfix to accept email for mydomain.io by setting mydestination or point MX records to a server that handles email for domain mydomain.io.