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If you prefer SMTP over HTTP, you can send emails using Lettr’s SMTP relay service.

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Prerequisites

Before you begin, make sure you have:
  1. Created an API key
  2. Verified your domain

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SMTP Credentials

Use the following settings to connect to Lettr’s SMTP server:
SettingValue
Hostsmtp.uselettr.com
Port465 (recommended), 587
Usernamelettr
PasswordYour API key

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Example

Here’s a basic example using swaks (Swiss Army Knife for SMTP): 
swaks --to [email protected] \
  --from [email protected] \
  --server smtp.uselettr.com:465 \
  --auth LOGIN \
  --auth-user api \
  --auth-password "your_api_key" \
  --tlsc \
  --header "Subject: Hello from Lettr" \
  --body "This is a test email sent via SMTP."