Our Parsha is about the battles of Yaakov to preserve his special way in service of Hashem. The primary battle is with Esav. At the beginning of the Parsha he meets his brother Esav near Pniel and at the end of the Parsha there is an allusion of the battle between the the Kingship of Mount Seir and the Jewish Monarchy -

 וְאֵ֙לֶּה֙ הַמְּלָכִ֔ים אֲשֶׁ֥ר מָלְכ֖וּ בְּאֶ֣רֶץ אֱד֑וֹם לִפְנֵ֥י מְלׇךְ־מֶ֖לֶךְ לִבְנֵ֥י יִשְׂרָאֵֽל

And these are the kings who reigned in the land of Edom before a king reigned over the Children of Israel.

"וישלח יעקב מלאכים" - Yaakov sent angels. The Rabbis say מלאכים ממש - actual bona fide angels [בר"ר ע"ה ד]. What is the nature of שליחות - agency, for angels? The Gemara derives שליחות from the laws of תרומה as the pasuk says "כן תרימו גם אתם" - So you should also separate the תרומה. The seemingly extra word "גם" comes to include a שליח as one who may separate Teruma  The Gemara expounds further "מה אתם בני ברית אף שלוחכם בני ברית" - Just as you are members of the covenant, so are your שליחים [Kiddushin 41b] and thus Goyim are not valid שליחים. The essence of שליחות is rooted in the idea that there is a connection between the sender and his agent, a connection that makes them like one body. Therefore, one can fulfill a Halachic obligation of his fellow in certain circumstances b/c it is as if the sender himself carried out the act. The Jews joined together in a covenant to keep the Torah which bounded them all together such that there is a concept of שליחות between fellow Jews while the Goyim who were not part of that covenant lack that connection which negates their capacity to be שליחים. Angels are ALSO not part of our special covenant so how did Yaakov send them as his שליחים?

The Avos kept the Torah before it was given [עי' אגרות הראיה א' עמ' קלה]. However, we have to understand what was the meaning of the Torah before it was given. It was not known in the form we have it today. We recognize the relationship between the world of nature and the Torah. Hashem looked in the Torah and created the world [ב"ר א,א]. The world is an outgrowth of looking into the Torah. It emerges that if one looks deeply into the phenomena of the world and nature one can perceive the foundations of the Torah. If not for the sin of Adam HaRishon we would not need a written Torah. Life itself would be naturally conducted based on the laws of the Torah. That is why it says "זה ספר תודות האדם" AFTER the sin of Adam HaRishon with the עץ הדעת. Only then a "sefer" was needed, a written Torah. 

Since the Avos came to fix the sin of Adam HaRishon, it emerges that their fulfillment of the Torah was from the period before the "ספר תולדות האדם", before the need for writing, and is built on the revelation of Hashem in nature. This aspect of keeping the Torah through which the laws of nature are conducted is the aspect of the Torah which relates even to angels. Chazal connect the pasuk "ברכו ה' מלאכיו גבורי כח עושי דברו לשמוע בקול דברו" [Tehillim 103, 20] to the idea that the angels keep the Torah and first say "נעשה" and only then "נשמע". Their connection to Torah was a natural one, an outgrowth of their very creation. So when the Jews said נעשה, they were saying that they will fulfill the Torah as an expression of their basic nature as they were made by Hashem, as it was until now [with the Avos]. Then נשמע - we will hear the new Torah that will be revealed to us. 

This connection between the Jews and angels is mentioned in the Medrash:

  בְּשָׁעָה שֶׁנִּגְלָה הַקָּדוֹשׁ בָּרוּךְ הוּא עַל הַר סִינַי יָרְדוּ עִמּוֹ כ"ב רְבָבוֹת שֶׁל מַלְאָכִים, שֶׁנֶּאֱמַר (תהלים סח, יח): רֶכֶב אֱלֹהִים רִבֹּתַיִם אַלְפֵי שִׁנְאָן, וְהָיוּ כֻלָּם עֲשׂוּיִם דְּגָלִים דְּגָלִים, שֶׁנֶּאֱמַר (שיר השירים ה, י): דָּגוּל מֵרְבָבָה, כֵּיוָן שֶׁרָאוּ אוֹתָן יִשְׂרָאֵל שֶׁהֵם עֲשׂוּיִם דְּגָלִים דְּגָלִים, הִתְחִילוּ מִתְאַוִּים לִדְגָלִים, אָמְרוּ אַלְוַאי כָּךְ אָנוּ נַעֲשִׂים דְּגָלִים כְּמוֹתָן, לְכָךְ נֶאֱמַר: הֱבִיאַנִי אֶל בֵּית הַיָּיִן, זֶה סִינַי שֶׁנִּתְּנָה בּוֹ הַתּוֹרָה. 

The Jews desired to have flags just like the angels.  This is the commonality between the Jews and the angels. We both have the orderliness of different groups standing under their particular flag to fulfill their unique task. That is an expression of the "נעשה" which is a common denominator between the Jews and the angels. 

This commonality of "נעשה" between humans and angels is what enabled Yaakov to send angels as his messengers. 

[עפ"י דרשת מרן הרב קוק סעודה שלישית וישלח תר"ץ]

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