$ cat /tmp/sendmail.txt
From: From-Name <email>
To: To-Name <email>
Subject: Test
Date: Mon, 03 Feb 2026 18:42:00 +0000
Test Content
$ sendmail -i -t -v < /tmp/sendmail.txt
$ cat /tmp/sendmail.txt
From: From-Name <email>
To: To-Name <email>
Subject: Test
Date: Mon, 03 Feb 2026 18:42:00 +0000
Test Content
$ sendmail -i -t -v < /tmp/sendmail.txt