Was a direct solution to this ever figured out? Note that there is a workaround. On the Parallels Pro forum, a user posted
that replacing the php_self() function in functions/strings.php in SQmail with the one from 1.4.9 worked to resolve this issue. The fact that you DON'T get this bug when using the php v5.2.x RPM from Remi suggests that it could possibly be a packaging issue or something in the php.ini file that is causing SQmail's 1.4.22 version of php_self() to fail, while the 1.4.9 version somehow escapes this problem.
If a direct solution was found (e.g. fixing something in php.ini, or repackaging the RPM somehow), please post or PM. I need to upgrade one of my Parallels Pro servers to php v5.3.x and was hoping to use the atomic RPMs for this, since others have had great luck with them (except for this SQmail issue).