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Replies & threads

Connect responses to their original messages.

Store Message-ID

Store message_id from the send response alongside your conversation ID. This RFC Message-ID differs from the outbound UUID.

Route replies

Send from your assigned custom receiving address, or set reply_to to it. Domain verification enables sending; an active receiving route and MX enable receiving.

Reply with context

Set in_reply_to to the incoming message’s Message-ID, including angle brackets. Read In-Reply-To and References from message headers/raw source to map conversations. There is no separate threads endpoint. Subject matching alone is unreliable.

Example
inboxit emails send --data @reply.json --idempotency-key reply-001

// reply.json
{"from":"hello@mail.yourbrand.com","to":"recipient@example.com","subject":"Re: Hello","text":"Thanks!","in_reply_to":"<original@example.com>"}