rightly vs sincerely

rightly

adv
  • In a right manner, correctly, justifiably. 

sincerely

adv
  • In a sincere or earnest manner; honestly. 

  • A conventional formula for ending a letter, used when the salutation addresses the person for whom the letter is intended by his or her name. 

How often have the words rightly and sincerely occurred in a corpus of books? (source: Google Ngram Viewer )