Oddly, I just got two e-mails in the last week from different people that had .dat files attached. I can’t open them on my Mac.
I did some googling, and I now understand what’s going on, so that’s not my question. My question is what’s the best way to open such a file on a Mac? I wasn’t too keen on downloading any of the freeware my google search turned up until I heard from the knowledgeable folks here.
Thanks!
What happens if you try opening one in Textedit? (I am aware that not all .dat files are text-based.)
I get a bunch of (I think) ASCII code. I tried selecting and converting to rich text, but that just gave me slightly different code. I’ve also tried saving the files in .jpg and .pdf format, but no go.
.dat can be anything. If you’re keen on using the terminal, the “file” command can identify a lot of formats.
“Using the terminal”. Is that what the kids are calling it these days? 
No, seriously, I don’t know what that means.
I think I would call that using the command prompt but maybe that’s just what PCs call it.
What were you expecting to be in the .dat files? Are you missing anything you expected from the sender? Was there supposed to be an attachment?
If the files are named winmail.dat it looks like those come from Outlook: How email message formats affect Internet email messages in Outlook - Microsoft Support
Perfect! Took me just a minute or two, and now I can open the files.
Thanks.