Emails not going through, ExplicitlyDiscarded, HADISCARD

Question

_{Tuesday, April 7, 2015 2:19 AM}

Hi,

We got an application sending out emails internally to our end users, it does so in bulks of about 50 or so. The application sends via a Exchange 2013 receive connector where the application server is listed as an allowed relay.

About 30% of the emails go through fine, but most are dropped in Exchange as such:

Timestamp SourceContext Source EventId

2/04/2015 13:02 ExplicitlyDiscarded SMTP HADISCARD

Its different recipients that get dropped every time and no other issues sending to any of these users.

All replies (5)

_{Friday, April 10, 2015 8:31 AM ✅Answered | 1 vote}

Turns out custom receive connectors are limited to 20 messages from 1 source at a time.

I increased that to 200 with:

set-receiveconnector -identity nameofconnector -MaxInboundConnectionPerSource 200

Problem solved!

_{Tuesday, April 7, 2015 6:40 PM | 2 votes}

Hello

HADISCARD: A shadow message was discarded after the primary copy was delivered to the next hop.

so check smtp receive and send connector log for email what is missing.

sorry my english

_{Tuesday, April 7, 2015 11:18 PM}

Thanks, but the .\hub\protocollog\smtpreceive and smtpsend are both pretty much empty, nothing since months back in there.

The receive connector used is a HubTransport connector, so that would be the logs to search, correct?

_{Wednesday, April 8, 2015 6:15 AM}

Hello

on  the  receive connector enabled verbose logging?

sorry my english

_{Thursday, September 13, 2018 5:47 PM}

An ExplicityDiscarded/HADISCARD event can happen for a variety of reasons. Another example would be an AmbiguousRecipient (dupe address).

Query the tracking log for "SourceContext" for more detail about the reason.

Get-MessageTrackingLog -Recipients [email protected] -Sender @xxxx.com | FL SourceContext

SourceContext : AmbiguousRecipient

SourceContext : CatDefer