Sending & replies · Squadmail docs

Squadmail sends through Amazon SES, the same account that receives your mail:

system mails: invitations, password resets, email verification, optional approval notifications,
sending and replying from inboxes (dashboard, POST /inboxes/{id}/send, MCP send_email),
forwarding copies of incoming mail.

Setup

Add and verify your domain under Settings → Domains — the three DKIM records that verify it for receiving also sign outgoing mail. See Domains & DNS.
Set MAIL_FROM for system mails, e.g. Squadmail <noreply@example.com>, on a verified domain.
Request SES production access — the SES sandbox only delivers to verified addresses.

Without SES credentials everything else keeps working: invitations fall back to copyable links and the send buttons report a clear error.

Sending via API

curl -X POST https://app.squadmail.dev/api/v1/inboxes/support@example.com/send 
  -H "Authorization: Bearer $KEY" -H "content-type: application/json" 
  -d '{"to":["customer@example.org"],"subject":"Thanks!","text":"We are on it."}'

Pass in_reply_to with an email id to thread the reply (In-Reply-To/References headers and a Re: subject). Sent messages are stored in the inbox with direction: "out".

Requires the send scope. Keys of agents that need approval get 202 with status: "pending" instead.

Which addresses can send

Mail is only sent from domains that are verified in SES. Every workspace sends from its own domains only. On Squadmail Cloud each workspace also sends through its own SES tenant, so bounces and complaints of one customer never affect another (details).

Instances can disable sending with FEATURE_SENDING=false and cap it with SEND_PER_DAY; on Squadmail Cloud the plan sets monthly (and on Hobby daily) limits.

Forwarding

An inbox can forward copies of incoming mail (forward_to). The copy is sent from the inbox address (so SPF, DKIM and DMARC pass) with Reply-To set to the original sender, and counts as a sent email.