I have seend this issue posted a couple times in the past, and wanted to see if anyone could provide their thoughts on what I'm experiencing.
Our sending IP was verified as unlisted as late as June 21 at 7AM PST, but an email we sent the next day June 22 at 930AM PST returned several bounces with a range of errors.
What I find interesting is that we received all bounces/errors on the same day, but the errors are so different and come from several unrelated recipient domains. All are referencing a SpamCop block.
550-"JunkMail rejected - XXX.mktomail.com [XXXXXX]:55650 is in an 550-RBL on rbl.websitewelcome.com, see Blocked - see 550 http://www.spamcop.net/w3m?action=checkblock&ip=XXXXXX"
550-"JunkMail rejected - sjsmtp.mktomail.com [XXXXXXX]:36064 is in an 550 RBL: Blocked - see https://www.spamcop.net/bl.shtml?XXXXXX"
550 spamcop.mimecast.org Blocked - see https://www.spamcop.net/bl.shtml?XXXXXX. - https://community.mimecast.com/docs/DOC-1369#550 [469OF93uOEyQiJ_Jghl1jw.us376]
But we are not listed:
Could there be a single root issue, or is it really the case that the error is rooted in each recipient's settings --- meaning we would need to contact each recipient who returned an error and address their settings individually?