SendGrid

Last updated: Nov 3, 2026

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Rationale

SendGrid is the service that Fluid Attacks uses to send transactional email from the Fluid Attacks platform. All the notifications, digests, reports, and onboarding messages that users receive by email go through it.

Fluid Attacks chose SendGrid over other alternatives for these reasons:

• It is SaaS oriented. The provider manages deliverability, sender reputation, and scaling.
• It gives a Python library that the backend uses to build and send messages with attachments and personalization for each recipient.
• It supports custom arguments on each message. Fluid Attacks uses them to tag each email with its template and subject.
• It gives an Event Webhook with signed events. Thus, Fluid Attacks can record when a user opens an email, clicks a link in it, reports it as spam, or unsubscribes from it.
• It supports domain authentication with DKIM. Fluid Attacks manages the DNS records of DKIM as code in Cloudflare.
• Auth0 supports it as an email provider, and Fluid Attacks configures it as code. Thus, the messages of Platform authentication come from the same domain as the rest of the Fluid Attacks platform.

Alternatives

Fluid Attacks used this alternative before it chose SendGrid.

Mailchimp Transactional

Mailchimp Transactional, formerly Mandrill, was the service that the Fluid Attacks platform used to send its email.

• Fluid Attacks got SendGrid when it added one-time passwords for login. As a result, two services did the same task.
• Fluid Attacks moved all the platform email to SendGrid. Thus, one provider sends all the platform email. Fluid Attacks also removed the analytics pipelines that read from Mandrill.

Usage

Fluid Attacks uses SendGrid for these tasks:

• Send the transactional email of the Fluid Attacks platform. This includes vulnerability and event notifications, consulting digests, report deliveries, environment connectivity alerts, and free trial onboarding. The backend of the Fluid Attacks platform keeps the templates of these messages.
• Send the verification and password emails of Platform authentication through Auth0.
• Record email engagement as audit events (refer to Platform audit logs). The audit logging service of Fluid Attacks receives the signed Event Webhook to do this.

Fluid Attacks does not use SendGrid for these tasks:

• Marketing campaigns and newsletters
• Alerts to the engineering team about infrastructure. Fluid Attacks uses SNS and Datadog for these alerts.