I run a website (swindonu3a.org.uk) on a shared hosting platform (22.214.171.124) organising activities for retired people. The email is too much for the shared hosting email policy so mail is sent via a web interface to SendGrid. Mail predominantly to Virginmedia and ntlworld is reported blocked on a periodic basis by SpamCop. SendGrid's recommended SPF and DMARC records are installed on the shared hosting website. Mail is defined as being sent from swindonu3a.org.uk and is only about 4k per month varying in batches from about 1000 for a monthly newsletter to more normally 10-100 for regular activities. All email is transactional in nature. My email is sent from SendGrid mail servers 126.96.36.199 or 188.8.131.52. Is there any way of determining whether email from swindonu3a.org.uk is triggering the blacklist registration of these servers or whether it is other SendGrid clients on those servers?