This is the actual report on which the email claims to be based.

This is a 48 detailed report on "The Challenges and Opportunities for Teaching Emotive and Controversial History 3-19"

In part 4 "Constraints to the Teaching of Emotive and Controversial History"
there is subsection 6 "Teachers Avoidance of Emotive and Controversial History"

to quote two paragraphs from this page.......

"Teachers and schools avoid emotive and controversial history for a variety of reasons, some of which are well-intentioned. Some feel that certain issues are inappropiate for particular age groups or decide in advance that pupils lack the maturity to grasp them.
Where teachers lack confidence in their subject knowledge or subject-specific pedagogy, this can also be a reason for avoiding certain content.
Staff may wish to avoid causing offence or appearing insensitive to individuals or groups in their classes. In particualr settings, teachers of history are unwilling to challenge highly contentious or charged versions in which pupils are steeped at home, in their community or at a place of worship. Some teachers also feel that the issues are best avoided in history, believing them to be taught elsewhere in the curriculum such as in citizenship or religious education.

For example, a history department in a northern city recently avoided selecting the Holocaust as a topic for GCSE course work for fear of confronting anti-Semitic sentiment and Holocaust denial among some Muslim pupils.
In another depsrtment, teachers were strongly challenged by some Christian parents for their treatment of the Arab-Isreali conflict and the history of the state of Israel that did not accord with the teachings of their denomination."

It is indeed extremely selective quoting to extrapolate from this small section and the example of a couple of schools to the scare headlines that appeared in certain UK newspapers following publication of the report.
However this does indeed seem to be the basis of the email quoted above.