AppleScript to send e-mail, using Apple's Mail, with multiple recipients, cc, bcc and attachments

AppleScript Mail Send.scpt

tell application "Mail"
	
	set theFrom to ""
	set theTos to {}
	set theCcs to {}
	set theBccs to {}
	
	set theSubject to ""
	set theContent to ""
	set theSignature to ""
	set theAttachments to {}
	set theDelay to 1
	
	set theMessage to make new outgoing message with properties {sender:theFrom, subject:theSubject, content:theContent, visible:false}
	tell theMessage
		repeat with theTo in theTos
			make new recipient at end of to recipients with properties {address:theTo}
		end repeat
		repeat with theCc in theCcs
			make new cc recipient at end of cc recipients with properties {address:theCc}
		end repeat
		repeat with theBcc in theBccs
			make new bcc recipient at end of bcc recipients with properties {address:theBcc}
		end repeat
		repeat with theAttachment in theAttachments
			make new attachment with properties {file name:theAttachment as alias} at after last paragraph
			delay theDelay
		end repeat
	end tell
	
	# macOS 10.12+ know bug
	# https://stackoverflow.com/questions/39860859/setting-message-signature-of-outgoing-message-using-applescript
	# set message signature of theMessage to signature theSignature
	
	send theMessage
	
end tell

theDelay is in seconds? milliseconds? thanks!

Seconds. And to be clear, the delay is to provide time for attaching an attachment to complete. So, if attaching a list of attachments is unstable, trying increasing the delay.

I am totally new to Applescript and coding in general and I have question:

How can I add attachments? If I add the file path to theAttachments I get an error message telling me that the file path cannot be converted in type alias.

Thanks in advance.

Cheers!