No individual criterion on this list is sufficient to condemn or exonerate a journal - many legitimate journals will not meet one or more of these criteria, and some predatory journals will meet some of these criteria.
However, taken together, a combination of all these factors should add weight to the journal being safe or unsafe.
Do not rely on the journal's own information for answers (such as whether it is listed in DOAJ, etc) - check the authoritative source.
(This area of the checklist is partly based on the Think.Check.Submit website. For more details on checking for predatory journals, more questions to check before publishing, and other sources to check, including checking journals from developing nations, go to Think.Check.Submit.)
Not conclusive, as legitimate journals and editors may use a registration service or privacy service, and predatory journals can create emails with a legitimate appearance, but this is sometimes another hint.