MXToolBox Blog Sending to Outlook.com Users gets more complicated

The arms race between spammers and Inbox Providers continues with Microsoft's recent announcement of changes to Outlook.com bulk emailer rules. Fortunately, there is good news: If you have already committed to Google and Yahoo Bulk Sender requirements, you are already covered. Keep doing what you are doing! What are the specifics? On May 5, 2025 [...]