...
Oct  4 06:24:12 kegilko-Mint postfix/smtp[6105]: 0EFA13A1A1C: to=<zzz@zzz.com>, relay=none, delay=534, delays=503/0.05/30/0, dsn=4.4.1, status=deferred (connect to smtp.yopmail.com[87.98.164.155]:25: Connection timed out)
Oct  4 06:28:42 kegilko-Mint postfix/qmgr[5797]: D0E8A3A1A16: from=<xxx@xxx.com>, size=662, nrcpt=1 (queue active)
Oct  4 06:28:42 kegilko-Mint postfix/qmgr[5797]: BF1763A1A20: from=<xxx@xxx.com>, size=666, nrcpt=1 (queue active)
Oct  4 06:29:13 kegilko-Mint postfix/smtp[6194]: connect to smtp.yopmail.com[87.98.164.155]:25: Connection timed out
Oct  4 06:29:13 kegilko-Mint postfix/smtp[6194]: D0E8A3A1A16: to=<www@www.com>, relay=none, delay=1128, delays=1098/0.01/30/0, dsn=4.4.1, status=deferred (connect to smtp.yopmail.com[87.98.164.155]:25: Connection timed out)
Oct  4 06:29:13 kegilko-Mint postfix/smtp[6195]: connect to mx3.hotmail.com[65.54.188.72]:25: Connection timed out
Oct  4 06:29:43 kegilko-Mint postfix/smtp[6195]: connect to mx2.hotmail.com[65.54.188.126]:25: Connection timed out
Oct  4 06:30:13 kegilko-Mint postfix/smtp[6195]: connect to mx1.hotmail.com[65.55.37.88]:25: Connection timed out
Oct  4 06:30:43 kegilko-Mint postfix/smtp[6195]: connect to mx1.hotmail.com[65.55.33.135]:25: Connection timed out
Oct  4 06:31:13 kegilko-Mint postfix/smtp[6195]: connect to mx2.hotmail.com[207.46.8.167]:25: Connection timed out
Oct  4 06:31:13 kegilko-Mint postfix/smtp[6195]: BF1763A1A20: to=<yyy@yyy.com>, relay=none, delay=755, delays=604/0.01/151/0, dsn=4.4.1, status=deferred (connect to mx2.hotmail.com[207.46.8.167]:25: Connection timed out)
Oct  4 06:33:42 kegilko-Mint postfix/qmgr[5797]: 0EFA13A1A1C: from=<xxx@xxx.com>, size=1197, nrcpt=1 (queue active)
Oct  4 06:34:12 kegilko-Mint postfix/smtp[6225]: connect to smtp.yopmail.com[87.98.164.155]:25: Connection timed out
Oct  4 06:34:12 kegilko-Mint postfix/smtp[6225]: 0EFA13A1A1C: to=<zzz@zzz.com>, relay=none, delay=1134, delays=1103/0/30/0, dsn=4.4.1, status=deferred (connect to smtp.yopmail.com[87.98.164.155]:25: Connection timed out
...

# 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 = kegilko-Mint
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = kegilko-smtp, kegilko-Mint, 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