Enum OutgoingEmailStage

Namespace

MailFathom.Domain.Delivery

Assembly

MailFathom.Domain.dll

States how far along its submission sequence one recorded outgoing email has durably reached.

public enum OutgoingEmailStage

Fields

Cancelled = 4

The send was withdrawn before it was delivered, and nothing was transmitted on its behalf.

Recorded = 0

The intent and the message are durable, and no SMTP command has been issued for them.

Every send starts here, and an attempt from here is safe because nothing has reached a submission server. A record stays here across an attempt that failed before the body went out, however far into the envelope it got: what a repeat of that costs is a connection, never a second delivery.

Refused = 3

The message will not be offered again, and the failure that ended it is on the record.

It covers a server's permanent refusal and every other way a send stops being attempted, which is what keeps a failed message visible instead of pending forever. Which of them ended it is read from the recorded failure and from the per-recipient outcomes rather than from a stage of its own.

Sent = 2

The server accepted the message for every recipient it had accepted, and nothing more is owed.

TransmissionBegun = 1

The message body has begun to go out, and the server's answer to it has not been read.

This is the one stage an attempt may not act on. A message transmitted twice is a second delivery rather than a repeat of the first, and unlike a duplicated local copy it cannot be withdrawn from the recipient it reached, so a record found here is reported as an unknown outcome rather than re-sent.

Remarks

The members are the stages an SMTP submission actually has rather than a generic queued, running, and done. That is what makes the value usable for resumption: an attempt reads the stage and continues from it, and the one point at which a repeat would deliver a second copy is recognized by the stage that precedes it rather than by inspecting a mailbox afterwards, which cannot tell a message this system sent twice from one it sent once.

TransmissionBegun is the whole reason the enumeration exists. A crash immediately after the message body went out and immediately before the server's answer was read leaves an attempt that cannot say whether the message was delivered, and the two possible answers call for opposite actions. Writing the stage before the transmission rather than after it narrows that window to something a restart can recognize; what is then done with a record found here is not decided by this type.

A message is Sent only from TransmissionBegun, which is the crash-safety invariant made structural: nothing is recorded as delivered that never recorded a transmission it could have been delivered by.

The stage is stored as its name so it stays readable in an ad-hoc audit query and survives any later reordering of this enum, which is the same reason the mutation stage and the stored content availability are stored that way.