line_length_hard_limit

Since: Version 2023.11.28-b5252a41

The functionality described in this section requires version 2023.11.28-b5252a41 of KumoMTA, or a more recent version.

The SMTP protocol specification defines the maximum length of a line in the protocol. The limit exists because there are SMTP implementations that are simply not capable of reading longer lines.

This option sets the limit on line length that is enforced by KumoMTA. The default matches the RFC specified limit of 998. When the line length limit is exceeded, KumoMTA will return a "line too long" error to the client.

You can raise this limit, but doing so may allow messages to be accepted that will be unable to be relayed to other SMTP implementations.