go-notification

Resend is the newest player in the transactional email space. Clean API, React Email as a first-class template system, generous free tier.

Pricing

Free — 3,000 emails/month, 100/day.
Pro — from $20/month for 50k emails and unlimited domains.
Enterprise — custom, includes dedicated IPs and SLAs.

Confirm at https://resend.com/pricing.

Setup

Sign up at https://resend.com.
Add a sending domain and verify via DNS.
Generate an API key from the dashboard (starts with re_).

main.go

import "github.com/gopackx/go-notification/channel/mail/resend"

notifier.RegisterChannel("mail", resend.New(resend.Config{
    APIKey:   os.Getenv("RESEND_API_KEY"),
    From:     "noreply@example.com",
    FromName: "My App",
}))

Configuration reference

Field	Type	Required	Description
`APIKey`	`string`	yes	Resend API key (`re_...`).
`From`	`string`	yes	Verified sender address.
`FromName`	`string`	no	Display name.
`ReplyTo`	`string`	no	Optional Reply-To header.
`Timeout`	`time.Duration`	no	HTTP timeout per send. Default: `30s`.

Good fit

Teams already using React / Next.js / Vercel.
Projects that want template ergonomics without a heavy enterprise vendor.
Startups that outgrow Mailgun's free tier but don't need SendGrid's compliance story.

Troubleshooting

403 validation_error: domain is not verified — verify your domain's DNS records in the Resend dashboard.
429 rate_limit_exceeded — free-tier hourly cap. Upgrade or throttle.
Mail from a new domain lands in spam — Resend can't warm your reputation for you. Ramp volume gradually for the first 2–4 weeks.