Mailflow understanding

Hello everyone,

Could you please help me to understand, what's going on with this message?

[PS] C:\Windows\system32>Get-TransportService | Get-MessageTrackingLog -Sender <sender> -MessageSubject "
subject" | sort timestamp | select ClientHostname, ServerHostname, ConnectorId, Source, EventId | fl


ClientHostname : mbx15-2.domain.local
ServerHostname : mbx15-2
ConnectorId    :
Source         : STOREDRIVER
EventId        : RECEIVE

ClientHostname : mbx15-1.domain.local
ServerHostname : mbx15-2
ConnectorId    :
Source         : SMTP
EventId        : HARECEIVE

ClientHostname : MBX15-2
ServerHostname : mbx15-1.domain.local
ConnectorId    :
Source         : STOREDRIVER
EventId        : SUBMIT

ClientHostname :
ServerHostname : mbx15-1
ConnectorId    :
Source         : SMTP
EventId        : HAREDIRECT

ClientHostname : mbx15-2.domain.local
ServerHostname : mbx15-1
ConnectorId    : MBX15-1\Default MBX15-1
Source         : SMTP
EventId        : RECEIVE

ClientHostname : mbx15-1
ServerHostname :
ConnectorId    :
Source         : AGENT
EventId        : AGENTINFO

ClientHostname :
ServerHostname : mbx15-1
ConnectorId    :
Source         : ROUTING
EventId        : TRANSFER

ClientHostname : mbx15-1
ServerHostname : ex-cas16-1.domain.local
ConnectorId    : exch14 -> Internet Mail
Source         : SMTP
EventId        : SEND

ClientHostname :
ServerHostname : mbx15-2
ConnectorId    :
Source         : SMTP
EventId        : HADISCARD

Could you descibe every hop in this log?