Next suspect mail flood: "Invoice 14 12 15" from "Thunderbolds Limited" / 2015-12-14

And the next flood of suspect e-mail messages:

This message contains 2 pages in PDF format.

[-- Attachment #2: fax00163721.xls --]
[-- Type: application/vnd.ms-excel, Encoding: base64, Size: 105K --]

[-- application/vnd.ms-excel is unsupported (use 'v' to view this part) --]

Probably more malware droppers. It seems some botnets are in great need for new systems to abuse.