Spamming is a super annoying issue, especially if you are worried about the misuse of your domain name by the spoofer. You didn’t send the email, but a program or script can easily add your email address to the “From” field so ordinary people will recognize this email is posted by you (which is you didn’t), at the end of the day, this will affect your domain reputation.
More than a year a go, I wrote about how to upgrade PHP 5.6 to PHP 7.0.
Now, PHP 7.0 will reached the end of its critical support through December 2018. After that date PHP community will no longer provides support for bugs. Following to PHP 7.0, PHP 7.1 will be put under discontinued support next year.