My mail provider does a pretty good job of filtering SPAM messages out. Just occasionally (maybe 1 in 1000) it puts things in the SPAM folder that is not SPAM, so I try to check before deleting SPAM for good. If I have not replied to an email, it went in SPAM and I missed it. Do not be afraid to send it again! Usually I respond within 24 hours.
Recently, my most common SPAM is "unable to deliver package" or similar. If you just confirm your details we can send you the package (and no doubt send you a nasty virus as a free bonus!!). Thankfully, SPAM is not an issue.