> ## Documentation Index > Fetch the complete documentation index at: https://ahasend.com/docs/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > AhaSend stores all message data in the EU. See /facts. > The API base URL is https://api.ahasend.com. Send the API key in the Authorization: Bearer header. See /api-reference/authentication. > Use send.ahasend.com for SMTP in the EU, or send-us.ahasend.com as a US connection point forwarding to the EU. Ports 25, 587 and 2525 use STARTTLS. Port 465 is not supported. See /smtp. > For send-only integrations, create an API Key v2 under Credentials → Add and scope it to messages:send:{your-domain}. See /send-api/credentials and /api-reference/scopes. # Transactional Email Glossary > Understand common transactional email terms used in AhaSend, including SMTP relay, DKIM, dedicated IP, bounces, suppressions, webhooks and idempotency. AhaSend's glossary explains the email terms used in these docs and links each term to its setup or reference page. ## Sending and Delivery | Term | Meaning | Read more | | ------------------- | ------------------------------------------------------------------------------------------ | ---------------------------------------- | | Transactional email | A message sent because of a user's action or an account event, such as a receipt or reset | [First send](/docs/quickstart) | | SMTP relay | A server that accepts email from your app and passes it toward the recipient's mail server | [SMTP settings](/docs/smtp) | | Email API | An HTTP service your app calls with a message and recipients | [REST API](/docs/send-api/send-email) | | Envelope sender | The SMTP sender used for delivery errors; it can differ from the visible From address | [Authentication](/docs/email-authentication) | | Return-path | The address used for delivery-status messages, normally based on the envelope sender | [Domain records](/docs/domains) | | MX record | A DNS record that names a domain's receiving mail servers | [Inbound routing](/docs/integrations/routing) | | STARTTLS | An SMTP command that upgrades a connection to TLS encryption before authentication | [SMTP settings](/docs/smtp) | | Dedicated IP | A sending IP assigned to one sender account rather than shared with other senders | [Dedicated IPs](/docs/scale/dedicated-ips) | | Warm-up | Gradually increasing legitimate sending while checking receiving systems' responses | [Deliverability](/docs/deliverability) | ## Authentication and Reputation | Term | Meaning | Read more | | ----------------- | ----------------------------------------------------------------------------------------------- | ---------------------------------------------------------------- | | SPF | A DNS policy describing which servers may send for the envelope sender's domain | [SPF, DKIM and DMARC](/docs/email-authentication) | | DKIM | A signature that lets receivers check a message against the signing domain's public key | [Authentication](/docs/email-authentication) | | DKIM selector | The name used to find the public key in DNS | [Domain records](/docs/domains) | | DMARC | A policy that ties passing SPF or DKIM to the visible From domain | [Authentication](/docs/email-authentication) | | Alignment | The domain match required between a passing authentication result and the From domain | [DMARC alignment](/docs/email-authentication#what-is-dmarc-alignment) | | Sender reputation | Receiving systems' view of a sender based on its sending history and signals such as complaints | [Deliverability](/docs/deliverability) | ## Results and Application Events | Term | Meaning | Read more | | --------------- | ---------------------------------------------------------------------------- | ----------------------------------------------------------- | | Acceptance | AhaSend agreed to process a message; the final outcome is still pending | [Sending responses](/docs/send-api/send-email) | | Delivered | The recipient server accepted the message; inbox placement is not guaranteed | [Delivery event](/docs/api-reference/webhooks/message-delivered) | | Bounce | A rejected delivery or a later notice that delivery failed | [Bounce handling](/docs/bounces) | | Suppression | A record that prevents sending to an address for its applicable domain scope | [Suppression rules](/docs/bounces) | | Webhook | An HTTP notification from AhaSend to your app when an event occurs | [Webhook setup](/docs/integrations/webhooks) | | Idempotency key | A value linking repeat API requests so a stored result can be replayed | [Limits and retry rules](/docs/api-reference/idempotency) | | Sandbox | A test mode that processes a message without delivering it to the recipient | [Sandbox mode](/docs/send-api/sandbox) | | Retention | How long message data or metadata is kept | [Retention settings](/docs/retention) | ## Related Guides * [Domain setup](/docs/domains), [DNS providers](/docs/dns) and [send-only API keys](/docs/send-api/credentials). * [REST API](/docs/send-api/send-email), [SMTP settings](/docs/smtp), [CLI quickstart](/docs/cli/quickstart), [Node.js SDK](/docs/guides/nodejs-sdk) and [Go SDK](/docs/guides/go-sdk). * [Plans and limits](/docs/facts), [delivery webhooks](/docs/integrations/webhooks) and [troubleshooting](/docs/troubleshooting).