Postfix: Difference between revisions

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==Docs==
=Docs=


*[http://www.postfix.org/ Homepage]
*[http://www.postfix.org/ Homepage]
*http://www.postfix.org/ADDRESS_CLASS_README.html
*[http://www.freebsddiary.org/postfix.php Postfix on FreeBSD]
*[http://www.zytrax.com/tech/survival/postfix.html Postfix survival guide]
*[http://www.zytrax.com/tech/survival/postfix.html Postfix survival guide]
*[http://wiki.apache.org/spamassassin/IntegratedInPostfixWithAmavis Postfix and Amavis]
*[http://wiki.apache.org/spamassassin/IntegratedInPostfixWithAmavis Postfix and Amavis]
*[http://www.akadia.com/services/postfix_spamassassin.html Postfix and SpamAssassin]
*[http://www.akadia.com/services/postfix_spamassassin.html Postfix and SpamAssassin]
*[http://hurring.com/howto/postfix_spamd/ postfix+spamd]
*[http://hurring.com/howto/postfix_spamd/ postfix+spamd]
*[http://www.irbs.net/internet/postfix/0609/1487.html postfix with spamassass-milter on freebsd]
*[http://www.postfix.org/faq.html FAQ]
*[http://www.postfix.org/faq.html FAQ]
*[http://wiki.linuxquestions.org/wiki/Postfix_with_clamav-milter Postfix with clamav-milter]
*[http://wiki.linuxquestions.org/wiki/Postfix_with_clamav-milter Postfix with clamav-milter]
*[http://postfixwiki.org/ Postfix wiki]
*[[postfix dovecot]]
*[[postfix dovecot]]
*[[postfix amavisd-new freebsd]]
*http://souptonuts.sourceforge.net/postfix_tutorial.html
*[http://macnugget.org/projects/postfixrelaymaps/ Setting up automatic relay_recipient_maps in postfix]
*http://wiki.kartbuilding.net/index.php/Postfix_SMTP#Blocking_Spam_with_spamhaus_and_Postfix
*[[Postfix on Debian]]
*http://www.postfix.org/VIRTUAL_README.html
*https://skrilnetz.net/setup-your-own-mailserver/
*[https://www.digitalocean.com/community/tutorials/how-to-configure-a-mail-server-using-postfix-dovecot-mysql-and-spamassassin How To Configure a Mail Server Using Postfix, Dovecot, MySQL, and SpamAssassin]
*[https://www.sidn.nl/en/news-and-blogs/hands-on-implementing-spf-dkim-and-dmarc-in-postfix Hands-on: implementing SPF, DKIM and DMARC in Postfix]
==Postfix and smtp auth/sasl==
*http://www.postfix.org/SASL_README.html
*[https://wiki.centos.org/HowTos/postfix_sasl Postfix/dovecot SASL and SSL/TLS guide on CentOS]
*[https://www.linode.com/docs/guides/postfix-smtp-debian7/ Configure Postfix to Send Email Using External SMTP Servers]
*[https://doc.dovecot.org/configuration_manual/howto/postfix_and_dovecot_sasl/ Postfix, dovecot and sasl]
*http://adomas.org/2006/08/postfix-dovecot/
*http://postfix.state-of-mind.de/patrick.koetter/smtpauth/smtp_auth_mailservers.html
*http://forums.macosxhints.com/archive/index.php/t-96919.html
*[https://www.sidn.nl/en/modern-internet-standards/hands-on-implementing-dane-in-postfix Implementing DANE in postfix]
===Postfix and Network Solutions certificates===
#The private key you created together with privkey.csr, readable for root only!
smtpd_tls_key_file = privkey.pem
#the certificate you received from NS
smtpd_tls_cert_file = /etc/ssl/MY.HOST.COM.crt
#NetworkSolutions_CA.crt and UTNAddTrustServer_CA.crt combined in a single file
smtpd_tls_CAfile = /etc/postfix/intermediate.pem
===SASL authentication failed; cannot authenticate to server smtp.office365.com[52.97.201.66]: no mechanism available===
install cyrus-sasl-plain
=HOWTO=
==Test smtp with telnet or openssl==
https://www.stevenrombauts.be/2018/12/test-smtp-with-telnet-or-openssl/
==DANE compliant config==
smtpd_tls_protocols = TLSv1.2, TLSv1.3
smtpd_tls_mandatory_protocols = TLSv1.2, TLSv1.3
smtpd_tls_exclude_ciphers =
      EXP, LOW, MEDIUM,
      aNULL, eNULL, SRP, PSK, kDH, DH, kRSA, DHE, DSS, RC4, DES, IDEA, SEED, ARIA, CAMELLIA, AESCCM8, 3DES,
      ECDHE-ECDSA-AES256-SHA384, ECDHE-ECDSA-AES128-SHA256, ECDHE-RSA-AES256-SHA384, ECDHE-RSA-AES128-SHA256,
      MD5, SHA
smtpd_tls_ciphers = high
smtpd_tls_mandatory_ciphers = high
smtpd_tls_dh1024_param_file = ${config_directory}/dh4096.pem
#for tlsv1.2, implicit in 1.3
tls_ssl_options = NO_RENEGOTIATION
smtpd_tls_eecdh_grade = ultra


==Postfix and LDAP==
==Postfix and LDAP==
*[[ Postfix LDAP ]]
*[http://www.akadia.com/services/postfix_separate_mailboxes.html Hosting Multiple Domains with Virtual Accounts]
*[http://www.akadia.com/services/postfix_separate_mailboxes.html Hosting Multiple Domains with Virtual Accounts]
*[http://www.postfix.org/LDAP_README.html#example_alias LDAP Support in Postfix]
*[http://www.postfix.org/LDAP_README.html#example_alias LDAP Support in Postfix]
Line 20: Line 75:
*http://gentoo-wiki.com/HOWTO_Postfix-LDAP_virtual_users_with_qmail_schema
*http://gentoo-wiki.com/HOWTO_Postfix-LDAP_virtual_users_with_qmail_schema
*http://www.ldapsource.com/content/ldap_postfix.html
*http://www.ldapsource.com/content/ldap_postfix.html
*http://www.boobah.info/howto/postfix-ldap.html
==Spam filtering==
*http://jimsun.linxnet.com/misc/postfix-anti-UCE.txt
*[http://postfwd.org/ Postfwd]
*[http://www.postfix.org/postscreen.8.html Postscreen]
*[http://rob0.nodns4.us/postscreen.html Postscreen cheatsheet]
*http://www.xnote.com/howto/postfix-spamassassin.html
*http://www.akadia.com/services/postfix_spamassassin.html
*[http://www.freesoftwaremagazine.com/articles/focus_spam_postfix/ Filtering spam with Postfix]
*[http://www.malgouyres.fr/linux/spamass-milter_postfix_en.html Postfix and spamass-milter]
==ldap and aliases==
*http://www.postfix.org/LDAP_README.html
*http://www.howtoforge.com/mandriva-directory-server-on-debian-etch-p3


===ldap and aliases==




Line 28: Line 97:
  man maildirquota
  man maildirquota


==Notes==
*postconf
*postsuper


==FAQ==
==Send mail via relay with authentication==
===Clean the postfix queue===
See [https://www.postfix.org/SASL_README.html SASL_README]
  mailq | grep ^[A-F0-9]| awk '{ print $1 }'| while read i;do postsuper -d  ${i};done
 
===Test relay authentication===
openssl s_client -connect server:25 -starttls smtp (-crlf if exchange)
 
 
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl/passwd
smtp_use_tls = yes
smtp_sasl_security_options = noanonymous
# if they use some self signed cert
smtp_tls_CAfile = /etc/postfix/cacert.crt
Exchange issues
# fixing "TLS library problem: error:0A000126:SSL routines::unexpected eof while reading" exchange feature?
tls_ssl_options = 0x80
#you might need this
smtp_sasl_mechanism_filter = !gssapi, !ntlm, static:rest
relayhost = [smtp.office365.com]:587
 
===sasl_password===
username:password
or
[relayname]:587 username:password
 
 
 
===Relaying via office365===
https://apiit.atlassian.net/wiki/spaces/ITSM/pages/1205567492/How+to+configure+postfix+relay+to+Office365+on+Ubuntu
 
 
====/etc/postfix/sasl_passwd====
[smtp.office365.com]:587 username@yourdomain:office365password
 
====/etc/postfix/generic====
root@whatever username@yourdomain
====/etc/postfix/main.cf====
relayhost = [smtp.office365.com]:587
 
smtp_tls_security_level=may
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_tls_security_level=may
smtp_generic_maps = hash:/etc/postfix/generic
 
=Tools=
*[https://internet.nl/test-mail/ Test-mail for DANE compliancy]
*postfwd
==pflogsumm==
Log analyzer
==vimbadmin==
[http://www.vimbadmin.net/ vimbadmin]
 
= Notes =
 
*postconf
*postsuper
 
== anti spam measures that work for me ==
 
smtpd_recipient_restrictions =
    permit_sasl_authenticated,
    reject_unverified_recipient,
    permit_mynetworks,
    reject_sender_login_mismatch,
    reject_invalid_hostname,
    reject_unknown_reverse_client_hostname,
    reject_non_fqdn_hostname,
    reject_non_fqdn_sender,
    reject_non_fqdn_recipient,
    reject_unknown_sender_domain,
    reject_unknown_recipient_domain,
    reject_unauth_destination,
    check_recipient_access  hash:/etc/postfix/recipient_access,
    reject_rbl_client bl.spamcop.net,
 
#reject_rbl_client safe.dnsbl.sorbs.net,
 
    reject_rbl_client b.barracudacentral.org,
    permit
 
== tls on outgoing mail ==
smtp_use_tls = yes
smtp_tls_security_level = may
TODO is all this really needed??
smtp_tls_CAfile = /etc/pki/tls/certs/ca-bundle.crt
smtp_tls_cert_file = /etc/postfix/ssl/domainname.com.pem
smtp_tls_key_file = /etc/postfix/ssl/domainname.com.key
smtp_tls_session_cache_database = btree:/var/lib/postfix/smtpd_scache
smtp_tls_loglevel = 1
 
=CentOS packages=
gf-plus repository
or epel :)
 
 
 
 
= FAQ =
==smtp vs smtpd==
smtpd = incoming
 
smtp = outgoing
 
 
==Stop trying to bounce to noreply@==
In '''transport_maps''' set
noreply@example.com discard
and in '''main.cf'''
transport_maps = hash:/etc/postfix/transport_maps
remember to
postmap /etc/postfix/transport_maps
and
postfix reload
 
==warning: no MX host for xxx has a valid address record==
Probably means the defined MX record does not resolve
=== Limit CC ===
 
/etc/postfix/header_checks
 
/^To:([^@]*@){50,}/ REJECT Sorry, your message has too many recepients.
/^Cc:([^@]*@){50,}/ REJECT Sorry, your message has too many recepients.
 
== fatal: bad string length 0 < 1: sendmail_path =  ==
Looks like a debconf feature, install mailutils and
postconf sendmail_path=/usr/sbin/sendmail
and probably also
postconf mailq_path=/usr/bin/mailq
postconf newaliases_path=/usr/bin/newaliases
then
postfix reload
to check, maybe more broke
 
 
== log subject ==
https://raymii.org/s/tutorials/Postfix_Log_message_from_to_and_subject_headers.html
 
Create file /etc/postfix/header_checks and put in:
 
/^[Ss]ubject:/  WARN
 
and in /etc/postfix/main.cf
 
header_checks = regexp:/etc/postfix/header_checks
 
&nbsp;
 
=== rate limit outgoing mail ===
 
*[http://steam.io/2013/04/01/postfix-rate-limiting/ Postfix rate limiting – Politeness goes a long way DEAD LINK]
*[https://wiki.deimos.fr/Postfix:_limit_outgoing_mail_throttling.html limit by domain]
 
Probably start with
 
smtp_destination_rate_delay = 5s
 
this seems safe for outlook.
 
== queue ==
 
=== Clean the postfix queue ===
 
  mailq | grep ^[A-F0-9]| awk '{ print $1 }'| sed 's/*//' | while read i;do postsuper -d  ${i};done
 
Or simple:
 
postsuper -d ALL
 
=== View message in queue ===
 
postcat
 
=== Delete message from queue ===
 
postsuper -d
 
=== Requeue mails ===
 
postsuper -r ALL
 
or
 
postqueue -f
 
 
===delivery temporarily suspended===
 
== Postfix as secondary MX ==
 
relay_domains = foo.com, bar.com
relay_recipient_maps =
          hash:/etc/postfix/relay_recipients
 
&nbsp;
 
== milter-reject 4.7.0 DNS timeout ==
 
Most likely caused by sid-filter, aka milter-sid, aka sid-milter. Try adding "-D" to the rc.conf or defaults or whatever file starting it.
 
== postqueue: fatal: Connect to the Postfix showq service: Permission denied ==
 
postfix set-permissions
 
== too many concurrent connections ==
 
If that's what you get sending to a server you don't control, check
 
initial_destination_limit (??)
smtp_destination_concurrency_limit
 
&nbsp;
 
== warning: SASL authentication failure: No worthy mechs found ==
 
could be missing cyrus-sasl-plain
 
&nbsp;
 
== Sender address rejected: need fully-qualified address ==
 
myorigin = /etc/mailname
 
If you're using mailutils, make sure fqdn is in /etc/hostname, double check with '''hostname -f'''
See also
mail --config-help
about contents of /etc/mailutils.conf, and
man hostname
 
==newaliases: fatal: bad string length 0 < 1: setgid_group ===
Probably Ubuntu (Debian?), comment out the setgid_group line
 
==warning: TLS library problem: error:1420918C:SSL routines:tls_early_post_process_client_hello:version too low:ssl/statem/statem_srvr.c:1686:==
 
  [[Category:Mail]]

Revision as of 13:56, 12 February 2024

Docs

Postfix and smtp auth/sasl

Postfix and Network Solutions certificates

#The private key you created together with privkey.csr, readable for root only!
smtpd_tls_key_file = privkey.pem

#the certificate you received from NS
smtpd_tls_cert_file = /etc/ssl/MY.HOST.COM.crt

#NetworkSolutions_CA.crt and UTNAddTrustServer_CA.crt combined in a single file
smtpd_tls_CAfile = /etc/postfix/intermediate.pem


SASL authentication failed; cannot authenticate to server smtp.office365.com[52.97.201.66]: no mechanism available

install cyrus-sasl-plain

HOWTO

Test smtp with telnet or openssl

https://www.stevenrombauts.be/2018/12/test-smtp-with-telnet-or-openssl/

DANE compliant config

smtpd_tls_protocols = TLSv1.2, TLSv1.3 smtpd_tls_mandatory_protocols = TLSv1.2, TLSv1.3 smtpd_tls_exclude_ciphers = 

     EXP, LOW, MEDIUM,
     aNULL, eNULL, SRP, PSK, kDH, DH, kRSA, DHE, DSS, RC4, DES, IDEA, SEED, ARIA, CAMELLIA, AESCCM8, 3DES,
     ECDHE-ECDSA-AES256-SHA384, ECDHE-ECDSA-AES128-SHA256, ECDHE-RSA-AES256-SHA384, ECDHE-RSA-AES128-SHA256,
     MD5, SHA

smtpd_tls_ciphers = high smtpd_tls_mandatory_ciphers = high smtpd_tls_dh1024_param_file = ${config_directory}/dh4096.pem

  1. for tlsv1.2, implicit in 1.3

tls_ssl_options = NO_RENEGOTIATION smtpd_tls_eecdh_grade = ultra

Postfix and LDAP

Spam filtering

ldap and aliases



man ldap_table
man maildirquota


Send mail via relay with authentication

See SASL_README

Test relay authentication

openssl s_client -connect server:25 -starttls smtp (-crlf if exchange)



smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl/passwd
smtp_use_tls = yes
smtp_sasl_security_options = noanonymous
# if they use some self signed cert
smtp_tls_CAfile = /etc/postfix/cacert.crt

Exchange issues 

# fixing "TLS library problem: error:0A000126:SSL routines::unexpected eof while reading" exchange feature?
tls_ssl_options = 0x80
#you might need this
smtp_sasl_mechanism_filter = !gssapi, !ntlm, static:rest
relayhost = [smtp.office365.com]:587

sasl_password

username:password

or 

[relayname]:587 username:password


Relaying via office365

https://apiit.atlassian.net/wiki/spaces/ITSM/pages/1205567492/How+to+configure+postfix+relay+to+Office365+on+Ubuntu


/etc/postfix/sasl_passwd

[smtp.office365.com]:587 username@yourdomain:office365password

/etc/postfix/generic

root@whatever username@yourdomain

/etc/postfix/main.cf

relayhost = [smtp.office365.com]:587

smtp_tls_security_level=may
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_tls_security_level=may
smtp_generic_maps = hash:/etc/postfix/generic

Tools

pflogsumm

Log analyzer

vimbadmin

vimbadmin

Notes

  • postconf
  • postsuper

anti spam measures that work for me

smtpd_recipient_restrictions =
   permit_sasl_authenticated,
   reject_unverified_recipient,
   permit_mynetworks,
   reject_sender_login_mismatch,
   reject_invalid_hostname,
   reject_unknown_reverse_client_hostname,
   reject_non_fqdn_hostname,
   reject_non_fqdn_sender,
   reject_non_fqdn_recipient,
   reject_unknown_sender_domain,
   reject_unknown_recipient_domain,
   reject_unauth_destination,
   check_recipient_access  hash:/etc/postfix/recipient_access,
   reject_rbl_client bl.spamcop.net,
  1. reject_rbl_client safe.dnsbl.sorbs.net,
   reject_rbl_client b.barracudacentral.org,
   permit

tls on outgoing mail

smtp_use_tls = yes
smtp_tls_security_level = may

TODO is all this really needed?? 

smtp_tls_CAfile = /etc/pki/tls/certs/ca-bundle.crt
smtp_tls_cert_file = /etc/postfix/ssl/domainname.com.pem
smtp_tls_key_file = /etc/postfix/ssl/domainname.com.key
smtp_tls_session_cache_database = btree:/var/lib/postfix/smtpd_scache
smtp_tls_loglevel = 1

CentOS packages

gf-plus repository or epel :)



FAQ

smtp vs smtpd

smtpd = incoming

smtp = outgoing


Stop trying to bounce to noreply@

In transport_maps set 

noreply@example.com discard

and in main.cf 

transport_maps = hash:/etc/postfix/transport_maps

remember to 

postmap /etc/postfix/transport_maps

and 

postfix reload

warning: no MX host for xxx has a valid address record

Probably means the defined MX record does not resolve

Limit CC

/etc/postfix/header_checks 

/^To:([^@]*@){50,}/ REJECT Sorry, your message has too many recepients.
/^Cc:([^@]*@){50,}/ REJECT Sorry, your message has too many recepients.

fatal: bad string length 0 < 1: sendmail_path =

Looks like a debconf feature, install mailutils and 

postconf sendmail_path=/usr/sbin/sendmail

and probably also 

postconf mailq_path=/usr/bin/mailq
postconf newaliases_path=/usr/bin/newaliases

then 

postfix reload

to check, maybe more broke


log subject

https://raymii.org/s/tutorials/Postfix_Log_message_from_to_and_subject_headers.html

Create file /etc/postfix/header_checks and put in: 

/^[Ss]ubject:/  WARN

and in /etc/postfix/main.cf 

header_checks = regexp:/etc/postfix/header_checks

 

rate limit outgoing mail

Probably start with 

smtp_destination_rate_delay = 5s

this seems safe for outlook.

queue

Clean the postfix queue

mailq | grep ^[A-F0-9]| awk '{ print $1 }'| sed 's/*//' | while read i;do postsuper -d  ${i};done

Or simple: 

postsuper -d ALL

View message in queue

postcat

Delete message from queue

postsuper -d

Requeue mails

postsuper -r ALL

or 

postqueue -f


delivery temporarily suspended

Postfix as secondary MX

relay_domains = foo.com, bar.com
relay_recipient_maps =
          hash:/etc/postfix/relay_recipients

 

milter-reject 4.7.0 DNS timeout

Most likely caused by sid-filter, aka milter-sid, aka sid-milter. Try adding "-D" to the rc.conf or defaults or whatever file starting it.

postqueue: fatal: Connect to the Postfix showq service: Permission denied

postfix set-permissions

too many concurrent connections

If that's what you get sending to a server you don't control, check 

initial_destination_limit (??)

smtp_destination_concurrency_limit

 

warning: SASL authentication failure: No worthy mechs found

could be missing cyrus-sasl-plain

 

Sender address rejected: need fully-qualified address

myorigin = /etc/mailname

If you're using mailutils, make sure fqdn is in /etc/hostname, double check with hostname -f See also 

mail --config-help

about contents of /etc/mailutils.conf, and 

man hostname

newaliases: fatal: bad string length 0 < 1: setgid_group =

Probably Ubuntu (Debian?), comment out the setgid_group line

warning: TLS library problem: error:1420918C:SSL routines:tls_early_post_process_client_hello:version too low:ssl/statem/statem_srvr.c:1686:

Retrieved from "https://wiki.dhits.nl/index.php?title=Postfix&oldid=8744"