Was this a scam?

[tearinghair]

Just checked my spam box in BT Yahoo. There was a message from American Airlines confirming details of my flight to Toledo. I'm not going to Toledo or anywhere else, for that matter. But I wondered whether someone had got hold of my credit card details, so, fool that I am, I opened the message and even (how stupid can I get?) replied saying it was nothing to do with me. Got an instant Mailer-daemon failure notice.
Do you think I've let the hackers in? I'm running a full system scan as I write; should I run malwarebytes as well? And how best to limit the damage, if damage there is?

[DTCwordfan]

yes to malware - cant do any harm

[Ann]

Run every cleaning programme you have!

[factor-fiction]

I don't think opening and reading the email can let hackers in- but if you click on a link in the email it could lead to an infection of your computer

[Nibble]

Run everything you have, then run again - if nothing..... THEN DON'T reply to anything in spam again. You've maybe been lucky this time, for the future think..... I didn't book it/ask for it....DON'T OPEN/REPLY TO IT. Have a Safe spam-free & Happy New Year.

[tearinghair]

Fingers crossed - yes I do know that I shouldn't open unsolicited emails; my excuse is that I'm absolutely exhausted and wasn't thinking straight. Thanks for your advice, everyone I'll do what you suggest.

[AlBags]

Don't worry about it .. It's not the end of the world.
At least you didn't run some executable and infected your whole system.

[tearinghair]

Thanks for the reassurance Albags.

[ChuckFickens]

"I don't think opening and reading the email can let hackers in- but if you click on a link in the email it could lead to an infection of your computer"

It can, malicious HTML code contained in emails can infect systems as soon as the mail is opened (although good AV should limit the risk)... That's the reason the reading pane in outlook is generally considered to be a security risk because viewing an email in the reading pane is the same as opening it, so if you have the reading pane active you can't delete emails without opening them.

[tearinghair]

So far so good....no obvious problems last night or this morning,so I'm hoping my momentary lapse in concentration hasn't had any serious consequences. At the very least it's reminded me that I need to back up files so that I can get them back if the hard drive gets infected. Again, thanks to everyone for your responses, and Happy New Year to all.