Delivery to the following recipient failed permanently:

     john@my.ip.add.ress.xip.io

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain my.ip.add.ress.xip.io by my.ip.add.ress.xip.io. [my.ip.add.ress].

The error that the other server returned was:
550 5.1.1 <john@my.ip.add.ress.xip.io>: Recipient address rejected: User unknown in local recipient table

# 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 "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# 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_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = my.ip.add.ress.xip.io
# alias_maps = hash:/etc/aliases
#virtual_alias_maps = hash:/etc/postfix/virtual

#alias_database = hash:/etc/aliases

myorigin = /etc/mailname
mydestination = my.ip.add.ress.xip.io, N-PC, 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

virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-mailbox-domains.cf
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf

$ /usr/sbin/postmap -vq john@my.ip.add.ress.xip.io
  mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf
...
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: result_format = %s
postmap: cfg_get_int: /etc/postfix/mysql-virtual-mailbox-maps.cf: expansion_limit = 0
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: query = <NULL>
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: table = users
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: select_field = id
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: where_field = id
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: additional_conditions =
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: domain =
postmap: cfg_get_str: /etc/postfix/mysql-virtual-mailbox-maps.cf: hosts = localhost
postmap: dict_open: mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf
postmap: dict_mysql_get_active: attempting to connect to host localhost
postmap: dict_mysql: successful connection to host localhost
postmap: dict_mysql: successful query from host localhost
postmap: dict_mysql_lookup: retrieved 1 rows
john@my.ip.add.ress.xip.io