This is the body of the message. Make the line longer than any header.
****
sudo exim -be -Mset $msg1
-From: $h_from:
-Subject: $h_subject:
+from: $h_from:
+subject: $h_subject:
message_body_size=$message_body_size
message_id=$message_id
message_exim_id=$message_exim_id
max_received_linelength=$max_received_linelength
recipients=$recipients
+TESTING_MACROS=$recipients
+(TESTING_MACROS)
****
exim -bs
mail from:<userz@test.ex>
quit
****
sudo exim -be -Mset $msg2
-From: $h_from:
-Subject: $h_subject:
+from: $h_from:
+subject: $h_subject:
message_body_size=$message_body_size
message_id=$message_id
message_exim_id=$message_exim_id