Why are IPv6 emails going to spam even with SPF?

Email marketer from Marketing Discussions shares that poor list hygiene (sending to old, invalid, or unengaged email addresses) can hurt your IPv6 reputation and cause spam filtering. Always maintain a clean and engaged email list.

Email marketer from Email Marketing Forum mentions the importance of having a properly configured reverse DNS (PTR) record for the IPv6 address, matching the sending domain. A missing or incorrect PTR record can negatively impact deliverability.

Email marketer from Email Marketing Tips Site notes that sometimes the issue isn't IPv6 itself, but the content of the email triggering spam filters due to keywords, links, or formatting. Content filters might be more sensitive with new or less-reputable IPv6 addresses.

Email marketer from Email Marketing Community mentions that some ISPs might require both SPF and DKIM records to pass for IPv6, even if SPF technically passes alone. They advise to always implement both authentication methods.

Email marketer from Reddit shares that many older spam filters don't properly handle IPv6 addresses, leading to misclassification even with SPF. He suggests ensuring the IPv6 address has a clean reputation and is not on any blacklists, as well as properly setting up DKIM.

Email marketer from Email Deliverability Blog shares that some ISPs still have less-than-perfect IPv6 support, leading to inconsistent filtering. Try segmenting your list and sending a smaller volume of IPv6 email to test deliverability.

Email marketer from StackExchange responds that although SPF passes, the IPv6 address range might be relatively new or shared, leading to a lower reputation score. She recommends warming up the IPv6 address gradually and monitoring its reputation.

Email marketer from Email Service Provider Forum responds that even with SPF, a new IPv6 address needs a 'warmup' period. Start with very low volumes of mail and gradually increase over weeks to establish a positive sending reputation.

Marketer from Email Geeks confirms that IPv6 addresses can have a reputation and may be treated with suspicion because it is easy to 'shoeshine'.

Marketer from Email Geeks shares that Google is strict on IPv6 emails lacking proper authentication (SPF and DKIM), having poor reputation, or being associated with spam. A new IPv6 address may also be treated with a poor reputation.

Expert from Email Geeks explains that IPv6 does have a reputation, usually applying to at least /56s, and probably bigger. Also, since there are no legacy IPv6 sources of mail there's no need to support unauthenticated mail from IPv6. However, similar to IPv4, it's less important than mailstream and content reputation.

Expert from Spam Resource, John Levine, responds that one reason IPv6 emails go to spam is that IPv6 address blocks are often assigned in larger chunks than IPv4, and if a small part of a block gets a bad reputation, the entire block can be affected. He recommends carefully monitoring the reputation of your entire IPv6 range.

Expert from Word to the Wise, Laura Atkins, shares that one of the significant reasons IPv6 email ends up in spam even with SPF is that authentication is more strictly enforced on IPv6 than on IPv4. She suggests that besides SPF, DKIM and DMARC are almost mandatory for IPv6 to achieve decent deliverability.

Documentation from Google Postmaster Tools explains that while SPF is a good start, DKIM is crucial for IPv6, especially since many legacy systems may not fully trust IPv6 without it. Also, monitor spam rates via Postmaster Tools to identify any deliverability issues specific to IPv6.

Documentation from Microsoft SNDS shares that they use their own reputation system, and IPv6 addresses are treated like any other IP. It advises regularly checking the SNDS portal for any issues related to your sending IPs, including IPv6.

Documentation from Validity discusses the importance of maintaining a positive sender reputation, which includes IPv6. They emphasize that reputation is a key factor in determining whether email reaches the inbox, regardless of authentication protocols.

Documentation from Spamhaus details that they also maintain IPv6 blocklists, and being listed on one of them will definitely cause deliverability issues. Check your IPv6 address against their blocklists to ensure it's clean.

Documentation from DMARC.org responds that for IPv6, like IPv4, implementing DMARC can increase trust by ISPs and help prevent email spoofing. DMARC requires both SPF and DKIM to be properly aligned, making it an important step for IPv6 email deliverability.

Documentation from RFC Editor details recommended anti-spam best practices for IPv6 mail streams, mentioning authentication, reputation, and volume control as important mechanisms for IPv6 email to be considered legitimate. It advises administrators to implement robust authentication techniques like SPF and DKIM and maintain accurate reverse DNS records.