Dovecot SIEVE – Sendmail process terminated abnormally, exit status 75

This error occurred on a dovecot 2.0.9 + postfix mail setup.

Dovecot error log displays:
Mar 24 14:01:32 lda(user@domain.tld): Error: Sendmail process terminated abnormally, exit status 75
Mar 24 14:01:32 lda(user@domain.tld): Error: sieve: msgid=<20150324130194.0C550EC00119@elabs10.com>: failed to redirect message to (refer to server log for more information)
Mar 24 14:01:32 lda(user@domain.tld): Error: sieve: execution of script /data/user@domain.tld/dovecot.sieve failed, but implicit keep was successful (user logfile /data/user@domain.tld/dovecot.sieve.log may reveal additional details)

Sieve log displays:

sieve: info: started log at Mar 24 14:01:32.
error: msgid=<20150324130194.0C550EC00119@elabs10.com>: failed to redirect message to (refer to server log for more information).

Postfix log displays:

Mar 24 14:01:32 svintpemail01 postfix/sendmail[6165]: fatal: open /etc/postfix/main.cf: Permission denied

Dovecot LDA settings at /etc/dovecot/conf.d/15-lda.conf (default: /usr/lib/sendmail or /usr/sbin/sendmail)

sendmail_path = /usr/sbin/sendmail

Postfix main.cf permissions

-rw-r----- 1 root root 5430 Mar 19 21:51 /etc/postfix/main.cf

Changing the permissions of main.cf would fix this issue. I’m always open for a better solution.
The dovecot also has some documentation about the inner working of LDA http://wiki.dovecot.org/LDA