Postfix, virtual aliases and catchall for undefined addresses

In Postfix 2.10.2, I have a setup with multiple domains and several virtual aliases to assign mail addresses to local users. It works fine as long as I do not add a catchall.

Before I used virtual aliases, I had a catchall defined with

local_recipient_maps =
luser_relay = catchall

but as I need to sort out mail addresses from different domains, I had to use virtual aliases.

Now postfix.org says I should do it like this, which I did:

/etc/postfix/main.cf:

virtual_alias_domains = example.com
virtual_alias_maps = hash:/etc/postfix/virtual

/etc/postfix/virtual:

postmaster@example.com account1
info@example.com       account1
sales@example.com      account2
@example.com         catchall

But if I do so, the catchall address grabs all my mail instead of just the mail to not explicitly defined addresses. Why is that and how do I change it?

I did postmap virtual and also restarted Postfix. There are no errors in the log, it just logs the delivery to the catchall address. And there is a warning "do not list domain example.com in BOTH mydestination and virtual_alias_domains", but I did not do that! I don't even have a mydestination directive. (There is one in the config below, but I added that after NickW suggested so.)

Here is my complete conf:

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
broken_sasl_auth_clients = yes
config_directory = /etc/postfix
home_mailbox = Maildir/
inet_interfaces = all
inet_protocols = all
mailbox_command = /usr/lib/dovecot/deliver -c /etc/dovecot/dovecot.conf -m "${EXTENSION}"
mailbox_size_limit = 0
mydestination = $myhostname
myhostname = mydomain.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtp_use_tls = yes
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_recipient_restrictions = reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_unauth_pipelining, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_authenticated_header = yes
smtpd_sasl_local_domain = $myhostname
smtpd_sasl_path = private/dovecot-auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_sender_restrictions = reject_unknown_sender_domain
smtpd_tls_auth_only = yes
smtpd_tls_cert_file = /etc/dovecot/dovecot.pem
smtpd_tls_key_file = /etc/dovecot/private/dovecot.pem
smtpd_tls_mandatory_ciphers = medium
smtpd_tls_mandatory_protocols = SSLv3, TLSv1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
tls_random_source = dev:/dev/urandom
virtual_alias_domains = $myhostname, myotherdomain.com
virtual_alias_maps = hash:/etc/postfix/virtual