Error when closing pipe to sendmail

Question

I am using perl module Mail::Builder::Simple to send email. It using the sendmail utility. I get this error when sending the email

error when closing pipe to sendmail:

Trace begun at /usr/local/share/perl5/Email/Sender/Transport/Sendmail.pm line 79

I am sure it's some permission issue, but not sure what exact permission is missing. Any idea what I am missing.

I see this error message in the file located at /var/spool/clientmqueue/:

550 5.0.0 Access denied
554 5.0.0 Service unavailable

Answer 1

I got this fixed

go to /etc/hosts.allow

add the line

sendmail:ALL at the end of the file and restart sendmail service.