Emails being accepted by large organisation

I understand how frustrating it can be to have your emails continuously end up in spam folders, especially when you're working closely with a public sector organization. Even with your emails meeting basic deliverability requirements, such as SPF records and a history of secure sending, there are still several factors that could be affecting the situation. Here are a few steps that may help improve deliverability:

1. Evaluate Email Content and Frequency: Even subtle triggers within the email content, subject lines, or the frequency of sending can sometimes cause emails to be flagged. Avoiding too many hyperlinks, using minimal capitalized words, and ensuring that the email language doesn't resemble typical spam triggers can all help.
2. Perform an Email Deliverability Test: A helpful way to assess if your emails contain elements that could be triggering spam filters is to run them through a https://campaigncleaner.com/tools/mail-tester/ to see if any deliverability improvements can be made. This tool can give you insights into any hidden red flags that may be causing your emails to end up in spam.
3. Implement DKIM and DMARC Records: Since you already have SPF, adding DKIM (DomainKeys Identified Mail) and DMARC (Domain-based Message Authentication, Reporting, and Conformance) records to your domain could enhance your email authentication. This is especially helpful with larger organizations that use more advanced security and filtering systems. DMARC, in particular, gives domain owners more control over who can send emails on behalf of the domain.
4. Check for IP Reputation Issues: Even though you’ve had no history of your domain being used insecurely, it’s worth checking the reputation of your IP address. If you’re using a shared server, other users on that server may affect the reputation. Services like MXToolbox can help you see if your IP has been flagged anywhere.
5. Adjust Sending Patterns: Sometimes, sending patterns, or "hopping," can be perceived as unusual or suspicious by email filters. To counteract this, consider testing a more consistent pattern of email communication or even reaching out to the public sector organization to explain your sending practices in detail.

I hope these suggestions help improve your email deliverability. Getting through strict spam filters can require some trial and error, but with consistent attention to these details, you should see improvements over time.