Sendgrid is one among the transactional email services that are best known to users and developers across the globe. It is even more popular as it is available for free unlike many of its competitors. Sendgrid is basically a cloud based transactional email service that caters delivery of bulk mails to its customers. It helps in sending purchase receipts to its subscribers and responses to customer enquiries through mails. It also aids in managing incoming mails. Sendgrid also offers an official plug-in to WordPress.