We’ve had a surge of PCs being infected by people clicking on “word document” invoices. These invoices have come from email addresses that are new to the person, but if you think about, you are just as likely to get an infected email from someone you know. Probably more so!
Your Antivirus will not always pick on on this “macro” malware and then your PC can get issues.
The simplest was to avoid trouble is never to click on the word attachments. Ask your suppliers to send you the invoice using PDF – I have not yet seen malware be transferred with a PDF.