Email providers

Configure email delivery with SMTP, Amazon SES, Postmark, or Mailgun.

Last updated Jul 15, 2026

Email providers send verification and recovery emails. You need one configured if you want email-based registration, account recovery, or email changes to work.

Tip (What we use in practice)

We usually use Postmark for events including Malta CTF, idek CTF, DiceCTF, and SekaiCTF. SES is inexpensive at higher volume when the event already uses AWS. SMTP works with any mail service that provides credentials, and Mailgun is another hosted option. Account limits and existing infrastructure usually matter more than the provider itself.

Configuration

Configure a provider and sender address. You can also add an email-specific logo:

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email:
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  provider:
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    name: emails/smtp
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    options:
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      smtpUrl: smtp://user:password@mail.example.com:587
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  from: noreply@example.com
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  logoUrl: https://example.com/email-logo.png # Optional

When email.logoUrl is unset, emails use the top-level logoLightUrl and logoDarkUrl values instead. The logo can also be set with the RCTF_EMAIL_LOGO_URL environment variable.

Note

Without an email provider, registration skips verification, account recovery is unavailable, and email-based division ACLs cannot be enforced.

Registration and recovery emails are rate limited by client IP and destination address, with or without captcha. Configure proxy trust correctly so the limiter sees the participant’s IP rather than the proxy’s.

Providers

Sends emails over SMTP using Nodemailer.

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email:
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  provider:
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    name: emails/smtp
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    options:
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      smtpUrl: smtp://user:password@mail.example.com:587
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  from: noreply@example.com

Option	Environment Variable	Description
`smtpUrl`	`RCTF_SMTP_URL`	SMTP connection URL

Sends emails through Amazon Simple Email Service.

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email:
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  provider:
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    name: emails/ses
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    options:
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      awsKeyId: AKIAIOSFODNN7EXAMPLE
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      awsKeySecret: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
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      awsRegion: us-east-1
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  from: noreply@example.com

Option	Environment Variable	Description
`awsKeyId`	`RCTF_SES_KEY_ID`	AWS access key ID
`awsKeySecret`	`RCTF_SES_KEY_SECRET`	AWS secret access key
`awsRegion`	`RCTF_SES_REGION`	AWS region

Warning

Make sure your SES account is out of the sandbox and the sender address is verified before you use it.

Sends emails through the Postmark API.

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email:
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  provider:
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    name: emails/postmark
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    options:
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      serverToken: your-server-token
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  from: noreply@example.com

Option	Environment Variable	Description
`serverToken`	`RCTF_POSTMARK_SERVER_TOKEN`	Postmark server token

Sends emails through the Mailgun API.

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email:
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  provider:
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    name: emails/mailgun
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    options:
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      apiKey: your-api-key
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      domain: mail.example.com
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  from: noreply@example.com

Option	Environment Variable	Description
`apiKey`	`RCTF_MAILGUN_API_KEY`	Mailgun API key
`domain`	`RCTF_MAILGUN_DOMAIN`	Mailgun sending domain