Hi - We've recently sent out a campaign and had a higher than normal hard bounce rate, with the majority of their causes listed as:
550 bl.spamcop.net An error occurred fetching the matches description - https://community.mimecast.com/docs/DOC-1369#550
Usually our hardbounces are related to generally bad data or a general blacklist, but we haven't had this before.
I've had a look in the provided link, but can't tell what has actually caused this?
We have recently updated out SPF and DMARC records and want to make sure something hasn't gone wrong with these..
I did a blog post covering this issue that you might find useful: