Outlook, Live, and Hotmail are now requiring SPF, DKIM, and DMARC for sending emails to improve IT security. Domains sending over 5,000 emails per day will soon need to comply with these standards, or their messages may be routed to Junk or even rejected if issues persist. Microsoft is urging high-volume senders to update their SPF, DKIM, and DMARC records before enforcement begins in May.