What is the difference between DKIM alignment and DKIM authentication and how do they relate to email bouncebacks and Hotmail blocks when using SFMC shared IPs?

Email marketer from Validity notes that shared IPs can lead to deliverability issues if other senders on the IP have poor sending reputations. This is because mailbox providers often use IP reputation as a factor in determining whether to accept or reject emails. Senders using shared IPs must monitor their reputation closely.

Email marketer from Hubspot highlights that high bounce rates can be caused by authentication issues (such as DKIM failures) or a poor sending reputation. If your emails aren't properly authenticated, receiving servers are more likely to reject them, contributing to bouncebacks. Additionally, shared IP addresses might suffer from the actions of other senders using that IP.

Marketer from Email Geeks guesses that DKIM Authenticated refers to whether or not the DKIM-Signature header validated, while DKIM Alignment means that the DKIM signing domain aligned with the visible From domain in the email message.

Email marketer from SendGrid shares that emails originating from shared IPs might encounter deliverability challenges due to the varied sending practices of all users on the IP. If some senders engage in spammy behavior, your email may get flagged as spam, even if you adhere to all sending best practices. Regular monitoring of sender reputation is crucial.

Email marketer from SparkPost notes that DKIM alignment directly impacts email deliverability. When the DKIM signature is aligned with the sending domain, it increases the likelihood that mailbox providers will trust the email and deliver it to the inbox. Lack of alignment can result in emails being filtered as spam.

Email marketer from EmailOnAcid shares that strict DMARC policies often require DKIM alignment. Without proper alignment, emails may fail DMARC checks and be rejected or sent to spam. This is especially relevant when sending on behalf of another domain.

Email marketer from Gmass says that bouncebacks can occur for many reasons, including authentication failures. If your DKIM isn't set up correctly, receiving servers may reject your emails. Additionally, temporary issues or problems with the recipient's server can cause bouncebacks.

Email marketer from StackExchange explains that if DKIM authentication fails, it's a strong signal to receiving mail servers that the email may not be legitimate. This can lead to bouncebacks, especially if the server has strict policies. The failure could be due to tampering, misconfiguration, or an incorrect DNS setup.

Marketer from Email Geeks explains that "Not authorized" means "not allowed," not "not authenticated." Hotmail bounces should be taken up with <http://postmaster.live.com|postmaster.live.com>.

Email marketer from Mailjet shares that DKIM alignment is when the domain used to sign the email (the d= domain) matches the domain in the email’s “From” address. DKIM authentication, on the other hand, confirms that the email’s signature is valid and hasn’t been tampered with. If these checks fail, email providers are more likely to flag your email as spam or reject it outright.

Email marketer from Litmus explains that using a shared IP means your sending reputation is influenced by other senders on that IP. If other senders engage in poor practices, your email deliverability can suffer. You may face increased bounce rates or have your emails marked as spam, even if you follow best practices.

Email marketer from Reddit notes that when using shared IPs through a service like SFMC, your sending reputation is somewhat tied to other users on that IP. If others send spam or have poor email practices, it can negatively impact your deliverability and lead to blocks by providers like Hotmail, even if your DKIM is properly configured.

Email marketer from Postmark explains that maintaining a good IP reputation is essential for email deliverability. If your IP's reputation is poor, mailbox providers are more likely to block your emails. This is especially important when using shared IPs, as your reputation is tied to other senders using the same IP.

Expert from Email Geeks explains that DKIM aligned means that the d= domain is aligned with the domain in the 5322.from address.

Expert from Word to the Wise explains that DKIM alignment means the domain used to sign the email (in the DKIM signature's 'd=' tag) matches the domain in the email's 'From:' header. This alignment is critical for DMARC compliance.

Expert from Spam Resource describes that shared IP addresses can cause deliverability problems if other users on the IP have poor sending practices. Mailbox providers may block or filter emails from the entire shared IP range, regardless of individual sender reputation.

Expert from Email Geeks says that Helo command rejected means either someone is blocking SFMC based on the HELO string or it’s a non-RFC compliant HELO. Given the EHLO is fine, it’s likely someone blocking ET.

Expert from Email Geeks shares that a failing body hash could be transient or due to different characters/template issues, and recommends checking the DKIM setup.

Expert from Email Geeks explains that DKIM authenticated means the DKIM signature passed.

Expert from Email Geeks suggests that MXToolbox’s DKIM verification may have bugs and might show errors when there are none and Marketer from Email Geeks references it being broken for years.

Expert from Email Geeks shares that SFMC will not work with Hotmail on your blocks. Hotmail doesn’t have a problem with SFMC, it has a problem with your emails, also if on a shared IP you may be in a dirty pool.

Documentation from RFC Editor details the DKIM authentication process. It states that a DKIM signature allows a recipient to verify that the message was signed by a party authorized to use the domain in the 'd=' tag of the signature. Proper authentication ensures that the message content hasn't been altered during transit.

Documentation from Microsoft outlines that Hotmail/Outlook.com may block emails from senders using shared IPs if those IPs have a poor reputation due to the actions of other senders using the same IP. Senders need to follow best practices to maintain a good sending reputation and avoid being blocked.

Documentation from Google Workspace Admin Help explains that DKIM adds a digital signature to outgoing email messages. This signature verifies to the receiving server that the message wasn't altered during transit and truly came from the domain it claims to be from. DKIM alignment refers to whether the domain in the 'd=' tag of the DKIM signature matches the domain in the 'From:' header of the email. Failing DKIM can lead to messages being marked as spam or rejected.