What is another word for by return mail?
Pronunciation: [ba͡ɪ ɹɪtˈɜːn mˈe͡ɪl] (IPA) 
By return mail is an expression commonly used to indicate that a response is expected in a timely manner. However, there are several synonyms that can be used in its place, depending on the context and preference of the speaker or writer. These include "promptly," "immediately," "without delay," "straightaway," and "as soon as possible." Other terms that can be used as equivalents are "by the next post," "by the next day," and "within 24 hours." Ultimately, the choice of words will depend on the level of urgency and the situation at hand.
