550 Dangerous attachment detected Anonymous 3 years ago updated 3 years ago Answered New InMotion hosting account: whenever I reply to an incoming email that has an image (eg company logo) in the sender's signature my email is quickly bounced back by the In-Motion server advising "550 Dangerous attachment detected" even though there is no attached file (eg pdf, jpg etc). If I remove the signature image in the message then the InMotion server will deliver it. Why the problem?