Script file is basically a text file containing a sequence of AutoCAD commands or Lisp functions.
The file can be created using Notepad but must be saved with file extension .SCR
Here's an example of a Script file (attached inside zip called eTransmit.scr) that first saves the current drawing and then runs the eTransmit command using the current Transmittal Setup:
; Begin Script File
_.Qsave
(command "_.-Etransmit" "_Create" (strcat(getvar"dwgprefix")(vl-filename-base(getvar"dwgname"))))
; End Script File
You can call a Script file from within the AutoCAD dwg using the SCRIPT command and then select the file.
Since there isn't an option to create a eTransmit Transmittal I would run the eTransmit command first and modify the Standard Transmittal setup to include the options required:
paullimapa_0-1760851968349.png
As @DGCSCAD pointed out you can run a Script file on all dwgs in a specific folder with Lee Mac's Script Writer app
Or if you want to run the Script on a selected set of dwgs then you can download my free Script Magician app from the Autodesk App Store:
paullimapa_1-1760852198942.png
https://apps.autodesk.com/ACD/en/Detail/Index?id=2118429164776866789&appLang=en&os=Win64
Then run Script Magician's added command SMD:
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Click the Default button to select script eTransmit.scr
Click Add button to select all the drawings to apply this script file on.
Finally click Start button to begin the individual drawing eTransmit process
FYI, Script Magician also has a command called SMF which like Script Writer can process a Script file on all dwgs inside a selected folder:
paullimapa_3-1760852364549.png