Network Programming in .NET

If you see this text:

Warning: Unverified sender : This message may not be sent by the sender that’s displayed. If you aren’t certain this message is safe, please be cautious when interacting with this email, and avoid clicking on any links or downloading attachments that are on it

Appearing on emails sent via AWS SES to Microsoft 365 Accounts, then there is a simple fix, that you can do – which is to apply DKIM to the domain.

I found that manually supplying the DKIM public/private key was easiest.

So. I created a keypair as follows;

openssl genrsa -out dkim_private.pem 2048
openssl rsa -in dkim_private.pem -pubout -out dkim_public.pem

Then, created a TXT DNS record on the domain named default._domainkey.<mydomain>.com

The records should look like this (using the public key, with spaces removed)

v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2uRIflp/tyXzZDgJ6WxEXoqh5jw==

Then, going in to AWS SES, I add a new identity, select domain, then press “Advanced DKIM”, then Provide DKIM authentication token (BYODKIM) – Then paste the private key, with spaces removed.

AWS then goes and checks your DNS, and hopefully within a few minutes you should get an email starting “DKIM setup SUCCESS”

Once that is in place, any email you send via SES on that domain will be DKIM signed, and trusted by Microsoft365, hopefully getting your delivery rate up!

https://www.smtpjs.com/