WRT {REM} you can’t put a Rem inside a function. putting the Rem inside an @For loop would be like trying to put a Rem inside an @SetField, or @dialogbox etc.
WRT {@MailSend} I have not tried to run @mailSend inside a loop, but I can understand why you would want to do it. I can only recommend using LS instead.
Your comment about REM is very clever - I would never have thought of it that way, but of course you’re 100% correct. Pity, though. It makes constructing and debugging loops much harder!
About the @MailSend - it’s indeed a very sad thing if this can’t work - would be a strong tool.