==== Checking tools/sites ====
https://www.emailsecuritycheck.net/index.html

https://www.mail-tester.com

http://www.isnotspam.com/

https://glockapps.com/

https://senderscore.org

http://www.anti-abuse.org

https://sendersupport.olc.protection.outlook.com/snds/data.aspx?wa=wsignin1.0 - MS SNDS






==== Postfix ====
https://www.wirehive.com/thoughts/5-top-tips-reviewing-postfix-mail-queue/

http://freesource.info/wiki/Dokumentacija/Postfix/antispam/restrictions

[[http://www.postfix.org/SMTPD_ACCESS_README.html|Postfix SMTP relay and access control]]

https://major.io/2013/04/14/remove-sensitive-information-from-email-headers-with-postfix/

https://www.linuxcnf.com/2018/11/how-to-change-default-mta-in-cent-os-7.html



==== Dovecot ====
https://wiki2.dovecot.org/HowTo/PostfixDovecotLMTP\

https://wiki.dovecot.org/MailboxSettings

https://wiki.dovecot.org/Namespaces

https://wiki2.dovecot.org/HowTo/AntispamWithSieve

https://wiki2.dovecot.org/Pigeonhole/ManageSieve/Configuration

https://wiki2.dovecot.org/Pigeonhole/Sieve/Examples

https://wiki.dovecot.org/Migration/Dsync

https://wiki.dovecot.org/PerformanceTuning





==== Rspamd ====
https://workaround.org/ispmail/stretch/filtering-out-spam-with-rspamd

[[https://github.com/rspamd/rspamd/issues/881|Bypass check for specific address]]





https://www.dcc-servers.net/dcc/


==== Sieve ====
https://mailutils.org/manual/html_chapter/Sieve-Language.html

https://p5r.uk/blog/2011/sieve-tutorial.html

[[https://dovecot.org/list/dovecot/2013-March/088899.html|[Dovecot] Sieve mark message as read]]

http://sieve.info/clients

https://github.com/thsmi/sieve/blob/master/nightly/0.2.3/sieve-0.2.3k.xpi


==== Webmail ====
https://www.rudraraj.net/how-to-install-roundcube-with-nginx/


https://wiki.dieg.info/postfix_backup_mx


==== Web mail admin panels ====
https://www.vimbadmin.net/

https://sourceforge.net/projects/postfixadmin

https://sourceforge.net/p/postfixadmin/wiki/Regex_aliases/


==== SPF, DKIM, DMARK, ARC ====

https://blog.returnpath.com/how-to-explain-authenticated-received-chain-arc-in-plain-english-2/

[[https://habr.com/ru/post/253705/|HowTo: DMARC]]


==== Other ====
http://diesel594.blogspot.com/2013/12/convert-imap-folder-names-to-readable.html

[[https://www.binarytides.com/linux-mail-with-smtp/|Send mail from the command line with an external SMTP server on Linux]]

https://serverfault.com/questions/846026/can-i-send-a-mail-through-gmail-with-swaks


==== Setup ====
https://thomas-leister.de/en/mailserver-debian-stretch/

https://www.c0ffee.net/blog/mail-server-guide




==== SMTP AUTH ====
PLAIN - one Base64 message after auth plain command
perl -MMIME::Base64 -e 'print encode_base64("\0user\@domain.com\0password");'
\0 (Null character) is required as a delimiter

LOGIN - two Base64 messages user and password
perl -MMIME::Base64 -e 'print encode_base64("user@domain.com");'
perl -MMIME::Base64 -e 'print encode_base64("password");'

described here - https://www.fehcom.de/qmail/smtpauth.html

openssl s_client -starttls smtp -connect server:port
openssl s_client -tls1_2 -connect server:port



==== Blacklists ====
Spamhaus test - https://blt.spamhaus.com