max_recipients_per_batch

Since: Version 2025.12.02-67ee9e96

The functionality described in this section requires version 2025.12.02-67ee9e96 of KumoMTA, or a more recent version.

Optional integer. Defaults to 100.

Specifies the maximum number of RCPT TO commands when sending a message that has multiple recipients.

If a message has more than this number of recipients then each chunk will be attempted successively in separate transactions. Those transactions will re-use the current connection, but if the connection is broken, the excess will remain eligible for immediate delivery which will typically continue on a new connection.