postfix email bounced: unknown user [closed]

On Ubuntu, I'm trying to send a test email using mail

This is my command:

mail -s 'Test e-mail' user@gmail.com

It then asks for Cc: then I hit ctrl + D to send it.

It doesn't show up in my email.

I check the logs using less /var/log/mail.log and this is what I get:

May  1 11:49:14 pm-XPS-13-9310 postfix/postfix-script[8038]: refreshing the Postfix mail systemMay  1 11:49:14 pm-XPS-13-9310 postfix/master[3067]: reload -- version 3.6.4, configuration /etc/postfixMay  1 11:49:44 pm-XPS-13-9310 postfix/pickup[8042]: F10523A60E86: uid=1001 from=<pete@pm-XPS-13-9310>May  1 11:49:44 pm-XPS-13-9310 postfix/cleanup[8053]: F10523A60E86: message-id=<20240501154944.F10523A60E86@pm-XPS-13-9310>May  1 11:49:44 pm-XPS-13-9310 postfix/qmgr[8043]: F10523A60E86: from=<pete@pm-XPS-13-9310>, size=354, nrcpt=1 (queue active)May  1 11:49:45 pm-XPS-13-9310 postfix/local[8055]: F10523A60E86: to=<user@gmail.com>, relay=local, delay=0.03, delays=0.02/0.01/0/0.01, dsn=5.1.1, status=bounced (unknown user: "user")May  1 11:49:45 pm-XPS-13-9310 postfix/cleanup[8053]: 0317F3A60E87: message-id=<20240501154945.0317F3A60E87@pm-XPS-13-9310>May  1 11:49:45 pm-XPS-13-9310 postfix/bounce[8056]: F10523A60E86: sender non-delivery notification: 0317F3A60E87May  1 11:49:45 pm-XPS-13-9310 postfix/qmgr[8043]: 0317F3A60E87: from=<>, size=2243, nrcpt=1 (queue active)May  1 11:49:45 pm-XPS-13-9310 postfix/qmgr[8043]: F10523A60E86: removedMay  1 11:49:45 pm-XPS-13-9310 postfix/local[8055]: 0317F3A60E87: to=<pete@pm-XPS-13-9310>, relay=local, delay=0, delays=0/0/0/0, dsn=2.0.0, status=sent (delivered to mailbox)

Here is my main.cf at /etc/postfix/

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destinationmyhostname = pm-XPS-13-9310alias_maps = hash:/etc/aliasesalias_database = hash:/etc/aliasesmyorigin = /etc/mailnamemydestination = $myhostname, localhost.$myhostname, gmail.com, pm-XPS-13-9310, localhost.localdomain, localhostrelayhost =mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128mailbox_size_limit = 0recipient_delimiter = +inet_interfaces = allinet_protocols = all

I added localhost.$myhostname based on this thread: Postfix - status=bounced (unknown user "myuser")

I still get the same issues.

I think the issue might be that myhostname = pm-XPS-13-9210. This is just the name of my computer and I didn't put this here. But what else would I change it to if this is the issue?

This person had the same issue but the solution is to a dead link:

postfix - status=bounced (unknown user)