Why are Sendgrid verification emails blocked by Mimecast when project invites are not?

Email marketer from Reddit shares that the volume and frequency of verification emails are usually lower than project invite emails. This difference in sending patterns could trigger anomaly detection systems within Mimecast. Invite emails may also be getting caught in filters due to being initiated by a real person, and a real action.

Email marketer from SparkPost shares that the content of verification emails might inadvertently trigger spam filters or specific rules within Mimecast. For example, using phrases like 'verify your account' or including certain types of links could be problematic.

Email marketer from Gmass suggests A/B testing different content and subject lines in the verification emails to identify what might be triggering Mimecast's filters and adjust accordingly.

Email marketer from Litmus shares maintaining a good domain reputation is crucial. Monitor your domain's reputation using tools like Google Postmaster Tools and address any issues promptly to prevent blocks.

Email marketer from Stack Overflow states that Mimecast, like other major providers, provides feedback loops. You should ensure that you're registered and monitoring these to identify any issues causing blocks specific to your account.

Email marketer from Neil Patel's Blog shares that warming up your IP address and domain can help improve your sending reputation. New domains/IPs are often viewed with suspicion by security filters such as Mimecast. It is possible your invite emails have built enough history to be trusted while your verification emails are being viewed as new.

Marketer from Email Geeks suggests contacting Mimecast support first to resolve the blocking issue, before reaching out to recipients.

Email marketer from Mailjet explains that using a dedicated IP address can significantly improve deliverability. Shared IPs can be negatively affected by other senders' practices, whereas a dedicated IP allows you to build your own reputation.

Email marketer from EmailonAcid explains ensuring all emails are properly authenticated using SPF, DKIM and DMARC will help build trust with receiving mail servers such as Mimecast and improve deliverability. It is possible your invite emails have these configured and the verification ones don't.

Expert from Word to the Wise says IP Warmup is critical for new sending IPs and domains. If project invites were sent from a warmed-up IP while verification emails are sent from a newer or less established IP, it can explain the discrepancy in deliverability.

Expert from Email Geeks states it's exceedingly unlikely that the envelope from is the same using two different ESPs, suggesting it's almost impossible.

Expert from Spam Resource emphasizes maintaining excellent list hygiene. Verification emails failing suggest potential issues with recipients who haven't explicitly opted in or are using outdated addresses, triggering Mimecast's spam traps.

Expert from Email Geeks suggests that solving the issue likely requires contacting the recipient or Mimecast support.

Expert from Email Geeks suggests reaching out to Mimecast because the blocking issue doesn't make sense, given the setup described.

Expert from Spam Resource shares about the importance of Feedback Loops and how registering with Mimecast’s feedback loop allows senders to receive reports on spam complaints. This information enables senders to identify and remove problematic recipients, which can help prevent future blocks.

Expert from Word to the Wise explains that high bounce rates from verification emails negatively impact sender reputation. Mimecast may be blocking based on accumulated negative reputation from these bounces, even if initial invite emails had a clean reputation.

Documentation from SendGrid Support explains that if DKIM is not properly configured for both sending domains/subdomains (project invites vs. verification emails), Mimecast could be more suspicious of the unauthenticated verification emails, leading to blocks.

Documentation from Mimecast shares that ensuring your sending IP addresses and domains are explicitly permitted in Mimecast's sender policies can prevent unexpected blocks. The invite emails may be benefitting from pre-existing rules.

Documentation from Auth0 shares to ensure Auth0 email settings are correctly configured to align with SendGrid's requirements. Incorrect configurations can lead to deliverability issues.

Documentation from Mimecast explains that common reasons for email blocks include sender reputation, content filters triggered by specific keywords or attachments in the verification email, or the recipient's personal block list.

Documentation from RFC explains that Sender Policy Framework (SPF) records must be correctly configured to authorize Sendgrid to send emails on behalf of your domain. Incorrect or missing SPF records can cause receiving servers like Mimecast to reject emails.