Postfix outgoing SMTP: "connection timed out"

I have a little problem with my postfix. The thing is that I can receive emails but when I send an email I get a Connection timed out error.

connect to outlook-com.olc.protection.outlook.com[104.47.5.33]:25: Connection timed out

This is happening with all the emails I send and not just with outlook. I already searched for solutions for this problem but couldn't find anything useful.

This is my main.cf:

# This file was automatically installed on 2019-06-27T15:11:55.824661
inet_interfaces = all
inet_protocols = ipv4
myhostname = webmail.apt-one.com
myorigin = $myhostname
mydestination = $myhostname
mynetworks = 127.0.0.0/8
smtpd_banner = $myhostname ESMTP
biff = no
unknown_local_recipient_reject_code = 550
unverified_recipient_reject_code = 550
# appending .domain is the MUA's job.
append_dot_mydomain = no
readme_directory = no
mailbox_size_limit = 0
message_size_limit = 11534336
recipient_delimiter = +
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
## Proxy maps
proxy_read_maps = proxy:unix:passwd.byname proxy:pgsql:/etc/postfix/sql-domains.cf proxy:pgsql:/etc/postfix/sql-domain- aliases.cf proxy:pgsql:/etc/postfix/sql-aliases.cf proxy:pgsql:/etc/postfix/sql-relaydomains.cf proxy:pgsql:/etc/postfix/sql-maintain.cf proxy:pgsql:/etc/postfix/sql-relay-recipient-verification.cf proxy:pgsql:/etc/postfix/sql-sender-login-map.cf proxy:pgsql:/etc/postfix/sql-spliteddomains-transport.cf proxy:pgsql:/etc/postfix/sql-transport.cf
## TLS settings
#
smtpd_use_tls = yes
smtpd_tls_auth_only = yes
smtpd_tls_CApath = /etc/ssl/certs
smtpd_tls_key_file = /etc/nginx/privkey.pem
smtpd_tls_cert_file = /etc/nginx/fullchain.pem
smtpd_tls_dh1024_param_file =
${config_directory}/dh2048.pem
smtpd_tls_loglevel = 1
smtpd_tls_session_cache_database =
btree:$data_directory/smtpd_tls_session_cache
smtpd_tls_security_level = may
smtpd_tls_received_header = yes
smtpd_tls_note_starttls_offer = yes
# Disallow SSLv2 and SSLv3, only accept secure ciphers
smtpd_tls_protocols = TLSv1.3, TLSv1.2, !TLSv1.1, !TLSv1, !SSLv2, !SSLv3
smtp_tls_protocols = TLSv1.3, TLSv1.2, !TLSv1.1, !TLSv1, !SSLv2, !SSLv3
smtp_tls_ciphers = high
smtpd_tls_ciphers = high
smtpd_tls_mandatory_protocols = TLSv1.3, TLSv1.2, !TLSv1.1, !TLSv1, !SSLv2, !SSLv3
smtp_tls_mandatory_protocols = TLSv1.3, TLSv1.2, !TLSv1.1, !TLSv1, !SSLv2, !SSLv3
smtp_tls_mandatory_ciphers = high
smtpd_tls_mandatory_ciphers = high
smtpd_tls_mandatory_exclude_ciphers = MD5, DES, ADH, RC4, PSD, SRP, 3DES, RSA, eNULL, aNULL
smtpd_tls_exclude_ciphers = MD5, DES, ADH, RC4, PSD, SRP, 3DES, RSA, eNULL, aNULL
smtp_tls_mandatory_exclude_ciphers = MD5, DES, ADH, RC4, PSD, SRP, 3DES, RSA, eNULL, aNULL
smtp_tls_exclude_ciphers = MD5, DES, ADH, RC4, PSD, SRP, 3DES, RSA, eNULL, aNULL
tls_preempt_cipherlist = yes
# Enable elliptic curve cryptography
smtpd_tls_eecdh_grade = ultra
# Use TLS if this is supported by the remote SMTP server, otherwise use plaintext.
smtp_tls_CApath = /etc/ssl/certs
smtp_tls_security_level = may
smtp_tls_loglevel = 1
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scach
smtp_tls_key_file = /etc/nginx/privkey.pem
smtp_tls_cert_file = /etc/nginx/fullchain.pem
## Virtual transport settings#
virtual_transport = lmtp:unix:private/dovecot-lmtp
virtual_mailbox_domains = proxy:pgsql:/etc/postfix/sql-domains.cf
virtual_alias_domains = proxy:pgsql:/etc/postfix/sql-domain-aliases.cf
virtual_alias_maps = proxy:pgsql:/etc/postfix/sql-aliases.cf
## Relay domains#
relay_domains = proxy:pgsql:/etc/postfix/sql-
relaydomains.cf
transport_maps = proxy:pgsql:/etc/postfix/sql-transport.cf proxy:pgsql:/etc/postfix/sql-spliteddomains-transport.cf
## SASL authentication through Dovecot#
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_sasl_security_options = noanonymous
## SMTP session policies#
# We require HELO to check it later
smtpd_helo_required = yes
# We do not let others find out which
recipients are valid
disable_vrfy_command = yes
# MTA to MTA communication on Port 25. We expect (!) the other party to
# specify messages as required by RFC 821.
strict_rfc821_envelopes = yes
# Verify cache setup
address_verify_map =
proxy:btree:$data_directory/verify_cache
proxy_write_maps = $smtp_sasl_auth_cache_name $lmtp_sasl_auth_cache_name $address_verify_map
# OpenDKIM setup
smtpd_milters = inet:127.0.0.1:12345
non_smtpd_milters = inet:127.0.0.1:12345
milter_default_action = accept
milter_content_timeout = 30s
# List of authorized senders
smtpd_sender_login_maps = proxy:pgsql:/etc/postfix/sql-sender-login-map.cf
# Recipient restriction rules
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated check_recipient_access proxy:pgsql:/etc/postfix/sql-maintain.cf proxy:pgsql:/etc/postfix/sql-relay-recipient-verification.cf reject_unverified_recipient reject_unauth_destination reject_non_fqdn_sender reject_non_fqdn_recipient reject_non_fqdn_helo_hostname
## Postcreen settings#
postscreen_access_list = permit_mynetworks cidr:/etc/postfix/postscreen_spf_whitelist.cidr
postscreen_blacklist_action = enforce
# Use some DNSBL
postscreen_dnsbl_sites = zen.spamhaus.org*3 bl.spameatingmonkey.net*2 dnsbl.habl.org bl.spamcop.net dnsbl.sorbs.net
postscreen_dnsbl_threshold = 3
postscreen_dnsbl_action = enforce
postscreen_greet_banner = Welcome, please wait...
postscreen_greet_action = enforce
postscreen_pipelining_enable = yes
postscreen_pipelining_action = enforce
postscreen_non_smtp_command_enable = yes
postscreen_non_smtp_command_action = enforce
postscreen_bare_newline_enable = yes
postscreen_bare_newline_action = enforce

Does anyone have a solution for this?

1 Answer

Lots of ISPs block outbound connections on port 25. ATT consumer/residential plans, as of the time of writing, all seem to block it. You may be able to change this in your ISP-provided router's configuration, or ask your ISP to allow it for your client at the gateway...