mpLowest

mpLowest = 4

Example

procedure ConfigureLowestPriorityMessage(Message: TIdMessage);
begin
  Message.Priority := mpLowest;
end;

Usage

mpLowest selects Velox's lowest mail-priority hint, generating non-urgent/low text headers and numeric X-Priority 5.

Additional Technical Info

mpLowest is the weakest priority hint in TIdMessagePriority. Generation emits Priority: non-urgent, X-Priority: 5 and Importance: low.

The example is source-reviewed and is not executed by the documentation workflow.

Behavior and boundaries

• The ordinal is four but X-Priority is five because Indy emits Ord(Priority) + 1.
• mpLowest and mpLow share textual headers; only X-Priority distinguishes them.
• Incoming text containing non-urgent or low maps to this extreme. The parser checks low/non-urgent before urgent/high so the urgent substring inside non-urgent is not misclassified.
• It has no effect on Velox queues, SMTP scheduling, retries, mailbox flags or delivery guarantees.

Use it only when recipients have agreed on the advisory convention. Do not encode business urgency or service priority solely in mail headers.

Errors, performance and concurrency

Assignment is constant-time. Header generation is stateful, can overwrite raw values and must not race with message mutation.

Related entries

• mpLow emits numeric level 4.
• mpHighest is the opposite extreme.
• TIdMessage.Priority documents parsing and headers.

External references

• RFC 5322 optional fields
• RFC 6648 on X- prefixes

Created 2026-07-15