Some of the best email marketing extensions for Magento include:
MageMonkey by Ebizmarts (Free)
Listrak Retail Solutions (Free)
Magento Email Marketing Pack by AheadWorks (Price different for each module)
DotDigital ($600 per month, with a free 30-day trial)
Abandoned Cart Email by Amasty (Prices starts from $89)
Advanced Newsletter by AheadWorks (Prices starts from $139)
Follow Up Email by Amasty (Price starts at $139)
If you want a custom email marketing extensions for your Magento online store, you may contact our Magento 2 development company for custom Magento extension development services or any kind of Magento eCommerce solutions.