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Dovecot isn't delivering emails from external servers

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Emails sent from other domains hosted by dovecot are being delivered, however emails from gmail, outlook and others are not being delivered.

I followed this tutorial: https://www.linuxbabe.com/mail-server/setup-basic-postfix-mail-sever-ubuntu (up to and including the 7th step (I did not add a spamfilter)) around 6 months ago and had it working for 6 months. I have since then swapped to another server and emails are not being delivered, from external servers, however I am able to send emails to external servers.

Upon migrating, I copied the maildir and all of its contents, and the /etc/dovecot and /etc/postfix directories

I am using MariaDB to store usernames, passwords and maildirs.

/etc/postfix/main.cf:

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

append_dot_mydomain = no

readme_directory = no

compatibility_level = 2

smtpd_tls_cert_file=/etc/letsencrypt/live/mx.najemi.cz/fullchain.pem
smtpd_tls_key_file=/etc/letsencrypt/live/mx.najemi.cz/privkey.pem
smtpd_tls_security_level=may
smtpd_tls_loglevel = 1
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache

smtp_tls_security_level = may
smtp_tls_loglevel = 1
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

#Enforce TLSv1.3 or TLSv1.2
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtp_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = mx.najemi.cz
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = $myhostname, localhost.$mydomain, 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
message_size_limit = 52428800

mailbox_transport = lmtp:unix:private/dovecot-lmtp
smtputf8_enable = no

virtual_mailbox_domains = proxy:mysql:/etc/postfix/sql/mysql_virtual_domains_maps.cf
virtual_mailbox_maps =
   proxy:mysql:/etc/postfix/sql/mysql_virtual_mailbox_maps.cf,
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf
virtual_alias_maps =
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_maps.cf,
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf,
   proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf

virtual_transport = lmtp:unix:private/dovecot-lmtp

virtual_mailbox_base = /var/vmail
virtual_minimum_uid = 2000
virtual_uid_maps = static:2000
virtual_gid_maps = static:2000

policyd-spf_time_limit = 3600
smtpd_recipient_restrictions =
   permit_mynetworks,
   permit_sasl_authenticated,
   reject_unauth_destination,
   check_policy_service unix:private/policyd-spf

milter_default_action = accept
milter_protocol = 6
smtpd_milters = local:opendkim/opendkim.sock
non_smtpd_milters = $smtpd_milters

/etc/postfix/master.cf:

smtp      inet  n       -       y       -       -       smtpd
submission     inet     n    -    y    -    -    smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_security_level=encrypt
  -o smtpd_tls_wrappermode=no
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
  -o smtpd_recipient_restrictions=permit_mynetworks,permit_sasl_authenticated,reject
  -o smtpd_sasl_type=dovecot
  -o smtpd_sasl_path=private/auth
smtps     inet  n       -       y       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
  -o smtpd_recipient_restrictions=permit_mynetworks,permit_sasl_authenticated,reject
  -o smtpd_sasl_type=dovecot
  -o smtpd_sasl_path=private/auth
pickup    unix  n       -       y       60      1       pickup
cleanup   unix  n       -       y       -       0       cleanup
qmgr      unix  n       -       n       300     1       qmgr
#qmgr     unix  n       -       n       300     1       oqmgr
tlsmgr    unix  -       -       y       1000?   1       tlsmgr
rewrite   unix  -       -       y       -       -       trivial-rewrite
bounce    unix  -       -       y       -       0       bounce
defer     unix  -       -       y       -       0       bounce
trace     unix  -       -       y       -       0       bounce
verify    unix  -       -       y       -       1       verify
flush     unix  n       -       y       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       y       -       -       smtp
relay     unix  -       -       y       -       -       smtp
        -o syslog_name=postfix/$service_name
showq     unix  n       -       y       -       -       showq
error     unix  -       -       y       -       -       error
retry     unix  -       -       y       -       -       error
discard   unix  -       -       y       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       y       -       -       lmtp
anvil     unix  -       -       y       -       1       anvil
scache    unix  -       -       y       -       1       scache
postlog   unix-dgram n  -       n       -       1       postlogd
maildrop  unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
uucp      unix  -       n       n       -       -       pipe
  flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)

ifmail    unix  -       n       n       -       -       pipe
  flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp     unix  -       n       n       -       -       pipe
  flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix  -       n       n       -       2       pipe
  flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman   unix  -       n       n       -       -       pipe
  flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
  ${nexthop} ${user}

policyd-spf  unix  -       n       n       -       0       spawn
    user=policyd-spf argv=/usr/bin/policyd-spf

/etc/dovecot/conf.d/10-mail.conf:

mail_location = maildir:~/Maildir

mail_home = /var/vmail/%d/%n/
namespace inbox {
  inbox = yes
}

postconf -n (output):

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
compatibility_level = 2
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
mailbox_transport = lmtp:unix:private/dovecot-lmtp
message_size_limit = 52428800
milter_default_action = accept
milter_protocol = 6
mydestination = $myhostname, localhost.$mydomain, localhost
myhostname = mx.najemi.cz
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
non_smtpd_milters = $smtpd_milters
policyd-spf_time_limit = 3600
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_tls_loglevel = 1
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtp_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_milters = local:opendkim/opendkim.sock
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, check_policy_service unix:private/policyd-spf
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
smtpd_tls_cert_file = /etc/letsencrypt/live/mx.najemi.cz/fullchain.pem
smtpd_tls_key_file = /etc/letsencrypt/live/mx.najemi.cz/privkey.pem
smtpd_tls_loglevel = 1
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtputf8_enable = no
virtual_alias_maps = proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf
virtual_gid_maps = static:2000
virtual_mailbox_base = /var/vmail
virtual_mailbox_domains = proxy:mysql:/etc/postfix/sql/mysql_virtual_domains_maps.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/sql/mysql_virtual_mailbox_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf
virtual_minimum_uid = 2000
virtual_transport = lmtp:unix:private/dovecot-lmtp
virtual_uid_maps = static:2000

dovecot -n (output):

auth_debug = yes
auth_debug_passwords = yes
mail_home = /var/vmail/%d/%n/
mail_location = maildir:~/Maildir
mail_privileged_group = mail
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    auto = create
    special_use = \Drafts
  }
  mailbox Junk {
    auto = create
    special_use = \Junk
  }
  mailbox Sent {
    auto = create
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    auto = create
    special_use = \Sent
  }
  mailbox Trash {
    auto = create
    special_use = \Trash
  }
  prefix =
}
passdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
protocols = imap lmtp imap lmtp
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
}
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
}
ssl = required
ssl_cert = </etc/letsencrypt/live/mx.najemi.cz/fullchain.pem
ssl_client_ca_dir = /etc/ssl/certs
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
ssl_min_protocol = TLSv1.2
ssl_prefer_server_ciphers = yes
userdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}

/etc/dovecot/dovecot.conf:

protocols = imap lmtp
!include_try /usr/share/dovecot/protocols.d/*.protocol
!include_try local.conf

/etc/dovecot/conf.d/10-auth.conf:

disable_plaintext_auth = yes
auth_username_format = %Lu
auth_mechanisms = plain
!include auth-sql.conf.ext
auth_debug = yes
auth_debug_passwords = yes

/etc/dovecot/conf.d/auth-sql.conf.ext:

passdb {
  driver = sql
  args = /etc/dovecot/dovecot-sql.conf.ext
}
userdb {
  driver = sql
  args = /etc/dovecot/dovecot-sql.conf.ext
}

/etc/dovecot/dovecot-sql.conf.ext:

driver = mysql
connect = host=localhost dbname=postfixadmin user=postfixadmin password=PASSWORD_HERE
default_pass_scheme = ARGON2I
password_query = SELECT username AS user,password FROM mailbox WHERE username = '%u' AND active='1'
user_query = SELECT maildir, 2000 AS uid, 2000 AS gid FROM mailbox WHERE username = '%u' AND active='1'
iterate_query = SELECT username AS user FROM mailbox

/etc/dovecot/conf.d/10-master.conf:

service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    mode = 0600
    user = postfix
    group = postfix
  }
}

service auth {
  unix_listener /var/spool/postfix/private/auth {
    mode = 0660
    user = postfix
    group = postfix
  }
}

/etc/dovecot/conf.d/10-ssl.conf:

ssl = required
ssl_cert = </etc/letsencrypt/live/mydomain.com/fullchain.pem
ssl_key = </etc/letsencrypt/live/mydomain.com/privkey.pem
ssl_min_protocol = TLSv1.2
anx avatar
fr flag
anx
"swapped to another server" could be anything between local configuration differences or failing to update the MX record accordingly. This question may only be answerable with logs (about rejected mail on your server and/or delivery failure reports from remote servers trying to deliver to your new host)
mangohost

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