Sending nodes are your email delivery channels — the SMTP servers or email service provider (ESP) connections that relay campaigns to recipients. You manage them under Setup → Sending Nodes, where you can add, test, copy, import/export, and activate or deactivate nodes. Multiple nodes let you distribute sending load or separate marketing from transactional mail.
When creating a node you pick a gateway and the form adapts to it. Supported gateways include Mumara ONE (Mumara's own sending solution — just an API token, with delivery reports built in), generic SMTP, Gmail (password or OAuth 2.0), Outlook, Yahoo, AOL, and ESP APIs such as Amazon SES, SendGrid, Mailgun, SparkPost, Mailjet, Postmark, SMTP2GO, Elastic Email, SendInBlue, ZeptoMail, and Mandrill. Each node also defines the sender name and email, optional reply-to, a Return-Path bounce address, a tracking domain for links and open pixels, and optional custom headers. For most ESPs, enabling Process Delivery Reports requires configuring a webhook (e.g. SNS for Amazon SES) on the provider side.
Worth knowing: always click Validate and send a test email before using a node in campaigns; Gmail/Yahoo/AOL usually need an app password when two-factor authentication is on. A momentary connection drop no longer pulls a node — the send is retried on a fresh connection with backoff, and a node is only auto-deactivated after repeated consecutive failures or a sustained outage. In a multi-node campaign the affected node is set aside while the others keep sending, and it rejoins automatically once it recovers; only when no active nodes remain does the campaign become System Paused. Deactivated nodes appear on the Issues page (Retry, Test Connection, or Set as Active to clear).