from string import ascii_lowercase as letters


email = 'KovalenkoDM@mpei.ru'
emailLetters = ''
emailSimbols = ''
for el in email:
    if letters.find(el.lower()) != -1:
        emailLetters += el
    else:
        emailSimbols += el
print(f'Letters in email are {emailLetters}\nSimbols in email are {emailSimbols}')