What are RashmimAlA Mantras? What's the importance of these mantras and Only Goddesses have these mantras ?
Rashmi Mala (Rashmi=Ray; Mala=Garland) Mantras are part of Sri Vidya worship. The Mantras are mentioned in the Parashurama Kalpa Sutra.
Details are also mentioned in the expository text Nityotsava's 3rd chapter, a text which is based (chapter by chapter) on Kalpa Sutra itself.
After a disciple is initiated into Sri Vidya, he/she must perform daily some rituals without fail, and the reciting these Rashmimala is part of that daily ritual (Nitya Karma).
It is done immediately after waking up from sleep. That is, one is allowed to do the chanting on one's bed itself.
The daily ritual for Sri Vidya disciple has the following steps (as per Nityotsava):
Ahnika Prakarana - Guru Dhyana (meditating on the Guru),
Pranasamjamanam (details omitted),
Chid Vimarsha (details omitted),
Hrida Mulavritti (reciting the Mula mantra in heart),
Rashmimala Smaranam (reciting or remembering the Rashmimala mantras),
Ajapa Gayatri Bhavanam (details omitted),
Bhuprarthana to Mukha Prakshalanam (from praying to Earth to rinsing the mouth),
Snanavidhi (rules of bathing),
Sandhya Vidhi (rules for Sandhya) ... etc ..
So, Rashmi Mala recitation is a prerequisite (and a limb of the whole Sadhana) to be completed before the disciple embarks upon the main ritual, which is to worship Goddess Sri Lalita Mahatripura Sundari in the Sri Chakra.
Nityotsava's 3rd chapter, which is titled Sri Krama, states:
Vakshyamanam rashmi mala mantramshcha ekavaram avartayeth |
Rashmisra gavartanam tu trai varnika vishayam ||
The given Rasmi Mala mantras should now be chanted once. Reciting these mantras are only prescribed for the Brahmins, Kshatriyas and Vaishyas.
Then it gives the list of around 30 or so Mantras along with mentioning the limbs of the Mantras. Dhyana Slokas, which are to be recited before chanting the Mantras, are also given.
And, no, the Mantras are not only for the Goddesses, several Mantras are there which are for the Gods.
The list (of deity/mantra) is as follows:
1 Abhayankara Mantra (Abhayankaramantrasya Gritasmada rishih, Trishtup chandah, Abhayankaro devata, tatprityarthe jape viniyogah)
2 Saura mantra
3 Pranava (om)
4 Turiya Gayatri
5 Chakshus Mati mantra
6 Viswa Vasu mantra
8 Tara mantra ( Tara mantrasya Matsya rishi, virat chandah, taramba devata, tat prityarthe jape viniyogah )
9 Namatraya mantra (for Vishnu)
10 Shiva Shakti Atmaka mantra
11 Amrita Mrityunjaya mantra (for Amritamrityunjaya Sadashiva)
12 Sruta Daharini Mantra (for Brahma)
13 Matrika (for Saraswati)
14 Sri Hadi Lopamudra
15 Bala Shadangam
16 Sampat Kari
17 Chanda Yogeswari
18 Parashambhu Natha
19 Para Mantra
20 Bala Tripura Sundari
23 Sri Vidya Guru Paduka
24 Laghu Shyama
26 Nakuli Vagiswari
27 Shyama Guru Paduka
28 Laghu Varahi
29 Swapna Varahi
31 Varahi Guru Paduka
32 Sri Purti Vidya
33 Mahapaduka Mantra.
So, these above 33 Mantras are known as the Rashmi Mala Mantras.