I can send email only with root, but not with non-root user

Hi,

I have RHEL 5.7 server. I am able to send mail from this server to my Inbox with root login, but not with a non-root user. Permission of sendmail.sendmail looks okay and emails are not holding up in the server, when I do mailq immediately after sending an email. Please suggest, what I am supposed to check or what I am missing.
Code:[jgreen@rhel-serv1-prod ~]$ cat /etc/mail/sendmail.cf | grep DS
DSwksb-mail1-prod.pedro.com
# Return-Receipt-To: header implies DSN request
# DHParameters (only required if DSA/DH is used)
[jgreen@rhel-serv1-prod ~]$
[jgreen@rhel-serv1-prod ~]$ mailx -v john.green@pedtel.com
Subject: test-non-root
.
Cc:
Null message body; hope that's ok
john.green@pedtel.com... Connecting to [127.0.0.1] via relay...
220 rhel-serv1-prod.pedro.com ESMTP Sendmail 8.13.8/8.13.8; Mon, 13 Apr 2020 15:45:52 -0700
>>> EHLO rhel-serv1-prod.pedro.com
250-rhel-serv1-prod.pedro.com Hello localhost.localdomain [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY
250 HELP
>>> MAIL From:<jgreen@rhel-serv1-prod.pedro.com> SIZE=58
250 2.1.0 <jgreen@rhel-serv1-prod.pedro.com>... Sender ok
>>> RCPT To:<john.green@pedtel.com>
>>> DATA
250 2.1.5 <john.green@pedtel.com>... Recipient ok
354 Enter mail, end with "." on a line by itself
>>> .
250 2.0.0 03DMjqn5028836 Message accepted for delivery
john.green@pedtel.com... Sent (03DMjqn5028836 Message accepted for delivery)
Closing connection to [127.0.0.1]
>>> QUIT
221 2.0.0 rhel-serv1-prod.pedro.com closing connection
[jgreen@rhel-serv1-prod ~]$
[jgreen@rhel-serv1-prod ~]$ mailq
/var/spool/mqueue is empty
Total requests: 0
[jgreen@rhel-serv1-prod ~]$
[jgreen@rhel-serv1-prod ~]$ ls -l /usr/sbin/sendmail.sendmail
-rwxr-sr-x 1 root smmsp 775064 Jul 28 2011 /usr/sbin/sendmail.sendmail
[jgreen@rhel-serv1-prod ~]$Thanks