the problem is that the email subject should be this...
email 1 subject : stockcode SKU0001 is below safety
email 2 subject : stockcode SKU0002 is below safety
email 3 subject : stockcode SKU0003 is below safety
..not this...
email 1 subject : stockcode SKU0001 is below safety
email 2 subject : stockcode SKU0001SKU0002 is below safety
email 3 subject : stockcode SKU0001SKU0002SKU0003 is below safety
which is whats happening.