anyone can explain following: 

I am receiving such non sense email adding pdf extension file and written following:

cp4a f5k tn1a hi3h ld0n c4o bp4w ht8j y0e nc7l ac6e z5p jc2v  7 2 5

from the these emails. 

from: 

Geronima Bretto <sarahrobinsonqlt1@gmail.com>

to:

alik44635@gmail.com,
mrwvtudaecip@gmail.com,
borovykh1951@gmail.com,
almazov.9797@gmail.com,
dimabelousow@gmail.com,
kentavor1488@gmail.com,
tota.krsk@gmail.com