Thanks you all for comments. I have made a decision to subscribed to dedicated IPs (credits: @slau).
The differentiating factor between our current AWS SES plan and the competitors (mentioned in the comments) is having a dedicated IP. With our current volume, none of the competitors are anyway near AWS SES costs. So, moving to a dedicated IPs thats cost 25$ extra not only solves our issue, but also no change in code/infrastructure.
The differentiating factor between our current AWS SES plan and the competitors (mentioned in the comments) is having a dedicated IP. With our current volume, none of the competitors are anyway near AWS SES costs. So, moving to a dedicated IPs thats cost 25$ extra not only solves our issue, but also no change in code/infrastructure.