Resolving relaying denied message from sendmail in same domain

If getting relaying denied message from sendmail when trying to connect within same domain, add:

FEATURE(relay_entire_domain)

to:

/etc/mail/sendmail.mc

then:

make -C /etc/mail

then:

restart sendmail

for more info refer to:

http://www.sendmail.org/tips/relaying.html

[excerpt]

For more precise tuning, several FEATUREs have been added to control relaying:

FEATURE(relay_hosts_only). Normally domains are listed in /etc/mail/relay-domains; any hosts in those domains match. With this feature, each host in a domain must be listed.
FEATURE(relay_entire_domain). Setting this feature allows relaying of all hosts within your domain. For example, on the host gateway.A.COM, this feature allows mail to or from any host in the A.COM domain. More precisely, this relays any host listed in the $=m class. This is equivalent to listing the name of the domain in /etc/mail/relay-domains.
FEATURE(access_db). This enables the hash database /etc/mail/access to enable or disable access from individual domains (or hosts, if FEATURE(relay_hosts_only) is set). The database format is described below.
FEATURE(blacklist_recipients). If set, this feature looks up recipients as well as senders in the access database.
FEATURE(rbl). NOTE: Thie feature is obsolete. Use FEATURE(dnsbl) in newer versions of sendmail. Enables rejection of mail based on the Realtime Blackhole List maintained at mail-abuse.org.
FEATURE(dnsbl). Enables rejection of mail based on the Realtime Blackhole List maintained at mail-abuse.org.
FEATURE(accept_unqualified_senders). Normally, sendmail will not accept mail from a sender without a domain attached -- for example, user instead of user@B.NET. This feature allows such users.
FEATURE(accept_unresolvable_domains). Normally, sendmail will refuse to accept mail that has a return address with a domain that cannot be resolved using the regular host lookups (a technique commonly used by spammers). This feature permits acceptance of such addresses. Unresolvable domains can be selectively accepted using the access database.
FEATURE(relay_based_on_MX). Setting this feature permits relaying for any domain that is directed to your host.