НА

Just FYI, in the subject lines of emails from Yaroslav is the word НА. 
This is Cyrillic text that looks like Latin letters, but is not.  I like 
to pronounce things sort of correctly, and in Russian, Н is pronounced 
like the English N.  In fact the name in Unicode for Н is "CYRILLIC 
CAPITAL LETTER EN".  (The lowercase is the same shape, but smaller.) 
The А (whose lowercase looks like 'a') is pronounced like an English A, 
so the pronunciation of НА is quite like how I pronounce the English 
word 'gnaw', since for me the 'g' is silent.

НА means the same thing here as 'Re:' does in email replies in English.