I found a site with some horrible slanders of Maulana Zakariyya(ra) after the reading the ones I got in the e-mail.

Hadhrat Shaykh Zakariyya (RA) is one of the greatest Muhaddith and scholars of our times. He has authored several books, amongst which are the commentaries of Sahih Bukhari, Muatta Imaam Maaliki, etc.

He has also compiled the book, Fadhaail-e-Aamaal which is an outstanding work as well as authentic. Thousands of people throughout the world have derived great benefit from this book. The claims of those entics are baseless.

The great work of 'Tabligh' is in no way the creation of British colonial powers. Rather, it was the noble work of the Ambiyaa (Alayhimus salaam), Sahaaba (Radhiallaahu Anhum) and passed on in this way to us. Allah Ta'ala uses different people for this noble work of Da'wat and Tabligh. Allah Ta' ala inspired Hadhrat Moulana Ilyaas Saheb (RA) who revived this noble work in this time and age. This work, is a means of uniting the Ummah, not disuniting the Ummah as alleged.

Also refer below

and Allah Ta'ala Knows Best

Mufti Ebrahim Desai
FATWA DEPT.

These were illustrious Ulama of the last century who played leading roles in the development and enhancements of Islamic spirit amongst the masses of India. They have also authored a number of books on diverse topics. One of the books authored by Shaykh Zakariyya (RA) is Fadhaail-e-Aamaal. Extensive use of this Kitaab is made by members of the Tabligh Jamaat in their Taleemi programmes. This is why they quote him so frequently in their Bayaans.

Moulana Ilyaas Saheb is quoted so frequently simply because he was the founder (or rather the reformer) of the Tablighi movement. These Ulama quote from the Qur'aan and Hadith or they commentate on the Qur'aan and Hadith. Hence, when people quote them, they are actually quoting a commentary of Qur 'aan and Hadith.