יג וַיֹּאמֶר מָרְדֳּכַי לְהָשִׁיב אֶל–אֶסְתֵּר אַל–תְּדַמִּי בְנַפְשֵׁךְ לְהִמָּלֵט בֵּית–הַמֶּלֶךְ מִכָּל–הַיְּהוּדִים
13. And Mordechai said to reply to Esther, “Do not imagine in your soul to escape the house of the king from all the Yehudim.
According to M’nos HaLevi, since Mordechai and Esther were using angels as their messengers, there was no longer the need for secrecy as implied by the word, “lihashlech” (“to send”). Angels do not need to be sent.