> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sendrealm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# SMTP

> Send email through Sendrealm using SMTP credentials

## SMTP Credentials

* **Host**: smtp.sendrealm.com
* **Port**: 587 (STARTTLS) or 465 (SMTPS)
* **Username**: `smtp` or `smtp:PROJECT_ID`
* **Password**: your API key

With username `smtp`, Sendrealm automatically selects the project that owns the envelope sender (`MAIL FROM`) domain. To select a project explicitly, use `smtp:PROJECT_ID` as the username.

In both modes, the API key must include `email.send`, the key must have access to the resolved project, and the sender domain must belong to that project. Missing, unauthorized, or ambiguously assigned domains are rejected. Existing `smtp` credentials remain valid and require no changes.