Malicious spam (malspam) pushing Emotet malware is the most common email-based threat, surpassing other malware families. In recent weeks, we have seen significantly more Emotets using a technique called “thread hijacking” that utilizes legitimate messages stolen from infected computers’ email clients. This technique is more effective than less sophisticated methods, which many people have now learned to spot. The approach is more successful at convincing potential victims to click on an attached file, or click on a link to download a malicious Word document with macros.”]
Source: https://unit42.paloaltonetworks.com/emotet-thread-hijacking/