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I followed the instructions in this post here's my postfix

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
append_dot_mydomain = no
readme_directory = no
# TLS parameters
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

myhostname =                                     
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination =, 2mm.compute-1.internal, localhost.compute-1.internal, localhost
relayhost = 
mynetworks = [::ffff:]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
luser_relay = ubuntu@localhost
local_recipient_maps =
virtual_alias_domains =
virtual_alias_maps = hash:/etc/postfix/virtual
#added below for DKIM
milter_default_action = accept
milter_protocol = 2

And here is my opendkim.conf

Syslog                  yes
LogWhy                  yes
UMask                   022
UserID                  opendkim:opendkim
KeyFile                 /etc/opendkim/20121002.private
Selector                20121002
Canonicalization        relaxed/simple
Mode                    sv
#SubDomains             no

KeyTable                refile:/etc/opendkim/KeyTable
SigningTable            refile:/etc/opendkim/SigningTable
ExternalIgnoreList      refile:/etc/opendkim/TrustedHosts
InternalHosts           refile:/etc/opendkim/TrustedHosts
Socket                  inet:8891@localhost

I'm only using one domain so I left SubDomains commented out. When I check with it says that there are no domainkeys or DKIM signature. I updated my DNS with my public key. This is on an amazon EC2 64 bit Ubuntu micro instance. I used sendmail command to test the signatures.

I'm to sure where else to look for a solution. Any ideas?

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up vote 3 down vote accepted

I found my own answer. the messages in /var/log/mail.log were instrumental in tracking down what was wrong. I'm still new to Linux, that was a tough lesson learned.

my problem was that in opendkim.conf I specified settings for:

  1. Domian
  2. KeyFile
  3. Selector

And also

  1. KeyTable
  2. SigningTable

I removed the tables and the emails were signed from all emails in my domain. That is after i restarted opendkim and postfix.

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