Microsoft Defender for Office 365 Ask Microsoft Anything

CRL55 - A bit of further clarification on Dhairyya's comment. You cannot remove this protection/control, as it is designed to prevent compromised users from affecting the organization/domain from compromise and abuse (i.e. email domain reputation protection). It is flagging cases where the user is sending out messages that are being detected as suspicious (spam) or malicious (phish/malware) within the broader Exchange Online environment. If left unchecked, it could mean that other emails from your organization get blocked or junked - in some cases by other third party cloud email services might be doing the same. This alert/protection most often triggers for people sending out legitimate emails when sending out advertising, newsletters, etc. that contain links. Office isn't intended for marketing email purposes, so the limits are set relatively low and may get triggered when sending to big volumes of users or distribution lists that have many names. You can adjust the users' limits up or down, but I'm not aware of how high you can set it. Bumping it up too much could affect domain reputation and should not be done en masse - instead limit it to specific users/groups. The specific policy to use is the outbound spam policy and target specific users try some higher message limits

Thanks for your question, CRL55. That is not possible as it when you get this alert it might be sign of an account compromise as the user might be sending malicious messages out. So, you need to actually need to check or tweak your outbound policy.