What are the tradeoffs between Notify and building email infrastructure yourself?

It depends on what you mean by “Notify” — if you mean a managed email notification service like GOV.UK Notify, SendGrid, Mailgun, Postmark, AWS SES, etc., the tradeoffs versus building your own email infrastructure are usually:

Using a managed notification service

Pros

• Fast to ship: You can send emails quickly without building delivery plumbing.
• High deliverability: Providers usually have good sender reputation, warm IPs, bounce handling, and spam-compliance tooling.
• Less operational burden: No need to maintain MTAs, retries, queueing, bounce processing, or IP reputation management.
• Compliance features: Often includes templates, audit logs, opt-out handling, and security controls.
• Scales well: Handles spikes and volume without much work on your side.
• Monitoring and analytics: Delivery, opens, clicks, failures, bounces, and webhooks are often built in.

Cons

• Cost: Can become expensive at scale, especially for high-volume transactional email.
• Vendor lock-in: Templates, APIs, and event webhooks may be provider-specific.
• Less control: You don’t control the sending stack, IPs, retry logic, or low-level tuning.
• Data/privacy concerns: Email content and recipient metadata pass through a third party.
• Feature limitations: Custom routing, advanced personalization, or unusual workflows may be constrained.

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Building your own email infrastructure

Pros

• Maximum control: Full ownership of sending logic, templates, routing, bounce policy, and data handling.
• Potentially lower marginal cost at very high volume: If you have the scale and expertise, self-hosting can be cheaper per email.
• Customization: Easier to implement bespoke workflows, internal compliance rules, or specialized delivery logic.
• Data residency/privacy: You can keep more of the pipeline in your own environment.

Cons

• Hard to do well: Email deliverability is tricky. You must manage SPF, DKIM, DMARC, IP warming, throttling, blacklist monitoring, etc.
• Operational overhead: You need queueing, retries, failure handling, bounce/complaint processing, observability, and incident response.
• Deliverability risk: Poor setup can land mail in spam or get IPs/domain reputation damaged.
• Ongoing maintenance: Mail servers require patching, abuse prevention, and constant tuning.
• Slower time to market: More engineering work upfront and ongoing.
• Hidden costs: Staff time and operational risk often outweigh infrastructure savings.

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Rule of thumb

• Choose a managed service if:

  • You need to send emails soon
  • Email volume is modest or medium
  • Deliverability matters and you don’t want to manage it yourself
  • You want reliability with minimal ops

• Consider building your own if:

  • You have very high volume
  • You have strong email/deliverability expertise in-house
  • You need strict control over data or delivery behavior
  • You can afford the operational complexity

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Practical middle ground

Many teams do a hybrid:

• Use a managed provider for most email
• Keep templates and message generation in-house
• Abstract the provider behind an internal API so it’s easier to switch later
• Route especially sensitive or high-value emails through one provider and bulk email through another

If you want, I can also give you a decision matrix for Notify vs self-hosting, or compare specific providers like GOV.UK Notify, SES, SendGrid, and Postmark.