Should I reply to e-mails that reached me by mistake (very low chance of being regular spam)?

Question

My name is fairly usual where I live and my e-mail address is {first_name}.{last_name}@very_large_provider.com, so from time to time I receive what is very probably legitimate e-mails sent to me by mistake. They usually are sent to {first_name}{last_name}@very_large_provider.com (the same without the dot), which the provider interprets as the one with a dot.

These e-mails:

• have various content (e.g. price offers with furniture schematics, advertising related materials that are supposed to reach some client, even projects to change some law sent by an assistant to some member of Parliament for approval).
• are written in my native language
• do not contain any disclaimer related to confidentiality of information or any type of disclaimer whatsoever
• the provider consider them as legitimate and it usually detects spam very accurately (sometimes too aggressively)
• almost all of them contains attachments (no executables or scripts, just Word documents and images)

I am tempted to reply to these e-mails and warn the sender about their mistake, as they seem legitimate.

Question: Should I reply to e-mails that reached me by mistake (very low chance of being regular spam)?

Answer 1

Depends on how far you want to go, I see two scenarios here: the first one is that the sender wants to establish a relationship with you so will be able to send you more messages after. Some Anti-abuse systems correlates this types of events (send and receive messages accepted) and creates a trust chain (The receiver receive messages from the sender X on the past). The second scenario is that the messages are a mistake. In any of both of them I will reply, if there is a mistake the good sender will notice this but the bad..... not sure of that.