Using the PHP compatibility checker against Comment Mail Pro in WordPress yields the following results:
Comment Mail Pro
FILE: /wp-content/plugins/comment-mail-pro/src/vendor/lusitanian/oauth/src/OAuth/Common/Http/Uri/UriFactoryInterface.php
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FOUND 1 ERROR AFFECTING 1 LINE
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17 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
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FILE: /wp-content/plugins/comment-mail-pro/src/vendor/lusitanian/oauth/src/OAuth/Common/Http/Uri/UriFactory.php
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FOUND 7 ERRORS AFFECTING 7 LINES
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19 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
76 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
95 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
118 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
134 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
144 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
160 | ERROR | Parameter shadowing super global ($_server) causes fatal error since PHP 5.4
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See Jason's findings here:
The error in a Comment Mail library: "Parameter shadowing super global ($_server) causes fatal error since PHP 5.4", is worth taking a closer look at. I suspect this is a false-positive as well, but it won't hurt to dig deeper on this one and be sure. That's being triggered in a library dependency in Comment Mail and not in the Comment Mail codebase itself.
If you're looking for problems, you'd want to put your attention on the composer.json file and do a review of the external library dependencies that it has.
Using the PHP compatibility checker against Comment Mail Pro in WordPress yields the following results:
Comment Mail Pro
See Jason's findings here: