It doesn't matter whether native speakers frequently use a certain word; what matters, however, is: how they pronounce it when they see a new word. Their native phonolgy
which they find hard to describe when you ask themputs some constraints on what are the plausible pronunciations of any new word.
In this case, the stress falls on the second syllable; you may end up with the following two variants.
ʃlɪ ˈmɑ zəl
ʃlɪˈmeɪ zəl