Delay reason: SMTP error from remote mail server after initial connection:
host c.mx.mail.yahoo.com [216.39.53.2]: 421 Message from (x.x.x.xip_removed) temporarily deferred – 4.16.50. Please refer to http://help.yahoo.com/help/us/mail/defer/defer-06.html

mas_domainkey.domain.com

mas is the selector

the key data goes into a txt record under a zone called  _domainkey.domain.com

Txt record will be called  mas._domainkey.domain.com

http://www.mailradar.com/domainkeys/

Exim : http://wiki.exim.org/DomainKeys

http://missysadmin.com/

http://www.socketlabs.com/services/dkwiz

http://www.smtpmta.com/

cpanel domainkey setup per domain
/usr/local/cpanel/bin/domain_keys_installer username

The private key is stored in /var/cpanel/domain_keys/private
The public key should be automatically written to your dns zone file. now if you host your dns somewhere else. Then you can just copy the data from the zone file and create the record where you host your dns ..

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setting up exim manually without cpanel using DKIMproxy

What is DKIMproxy

Political answer:

SOLUTION:
What ‘Too many hops’ usually means is that someone has set up e-mail such that it is forwarding between two addresses – a ‘mail loop’ has been set up inadvertently. You should send e-mail to the postmaster at the site (the site is what comes after the @ sign in the person’s e-mail address) and ask if he or she can look into the problem. For example, if you have this problem when
sending mail to johndoe@netcom.com, send a copy of the message to postmaster@netcom.com asking for an investigation of the problem.

Geek Answer:

Mostly likely you have your email being forwarded to yourself via the mail server settings.

You will need remote access to the server hosting the smartermail application. Locate the domain folder and then user folder. Copy the inbox information to another folder outside of the users folder.

Now login into the interface and remove the email users and recreate the user. now move the inbox folder back into the user’s folder.

Another option is to remove the addressbook.xml file and remove the root.cfg file .. This should delete the address book also . ** this has not been confirmed ******