Know what spec you need, and then make a judgement. 2nd hand laptops are rarely good value (ignoring niche needs like car diags etc).
For general internet browsing and email, I'd be looking at a minimum of:
3rd gen Core i3
2Gb RAM
No discrete video adapter (i.e., you want to use the one built in the CPU)
SSD of a usable size for your needs, generally at least 120Gb, more if you want a lot of photos/music/video on. Don't bother with traditional HDD, unsuitable for Win10
"Old Trusty", my 10 yr old HP 6720s that I'm about to boot up to get in the bath (this poxy MacBook is too unstable on the edge of the bath), is a Core Duo 2Ghz, 2Gb RAM, 965 chipset/video and 120Gb SSD... ...so doesn't meet the spec I've given. But I've tuned it to run at a reasonably sensible speed, but browsing sites littered with ads (most forums, and egay etc) do make it stutter badly, due to lack of shear CPU grunt.