I want to show preview text with subject in subject line not the body of the email. before this I'm showing body f the email with the subject in subject line.I'm using the Golang AWS SES-v2 https://pkg.go.dev/github.com/aws/aws-sdk-go-v2/service/sesv2 package for sending emails
I want the MIME to show preview text
Full MIME for preview text
There is no such thing as "MIME for preview". There is no standard to mark a specific part of the mail for preview.
If the mail client shows parts of the mail body in addition to the subject of the mail in preview is very specific to the mail client or maybe even its configuration. This means it will also differ between clients and one cannot rely on anything here.
Therefore, whatever you do it might be rendered differently in different mail clients.