Ask HN: Are linode IP blocks under yahoo block list

I have a website launched with linode. From past few days, I notice "Unfortunately, messages from xx.xx.xx.xx weren't sent. Please contact your Internet service provider since part of their network is on our block list."

I opened a case with linode and they responded back very quickly:

Hello,

Thank you for contacting us. Unfortunately, we wouldn't have any additional information about why certain email services are rejecting your emails; you might want to contact those services directly for more information.

Users doesn't receive mail when they use yahoo, but when they use gmail, mail is in spam folder. What should be my next steps? Please feel free to suggest me some check list.