And I mean really colorful, as in it has signs and colors. Like the one in the featured image. If you look in their source, they look like this: Subject: =?utf-8?b?8J+QlfCfkIhZb3UgY2FuIHNhdmUgb24gcGV0IGZvb2Qg8J+QlfCfkIg=?= As it can be seen on this page, there are all possible symbols described: http://www.unicodetools.com/unicode/codepage-utf8.php All it has to do is to force the email client to display them. Most of the time, it actually works, as can be seen above. Sometimes, it doesn’t, even if the symbols are correctly set up: Subject: =?utf-8?q?=F3=BE=86=93_sorin=2Emustaca=2C_Discount_Dental_Implants_in_You?= =?utf-8?b?ciBBcmVhIPO+hpM=?= You can actually see the character’s code number 🙂 So, are they dangerous ? Not really… usually. I can imagine though, that if the mail client has a vulnerability when it displays certain characters, some bad guys could use it to exploit it. This way it could, in theory, trigger an unwanted execution of a script or download a file and execute it.