Hi Duy.
Did you solve this problem? whe have a similar problem here.
Until now, we don't find a solution. [ UnknownIncomingEmailIntegrationError]
Mailbox Async Processing State
mailboxid : fd5ff995-4b76-e811-80e8-005056ba2740
hostid: Null
processingstatecode : 0
processinglastattemptedon : 07/03/2019 16:56:36
Mailbox Synchronization Methods (2 is server-side sync or email router, 1 is Outlook sync, 0 is none)
incomingemaildeliverymethod : EmailRouter
outgoingemaildeliverymethod : EmailRouter
actdeliverymethod : OutlookClient
Mailbox Enabled State
enabledforincomingemail : True
enabledforoutgoingemail : True
enabledforact : False
Mailbox Idle State (shows how many times the mailbox was processed with no email items or Appointments, Contacts and Tasks to synchronize)
noemailcount : 6
noactcount : 0
Mailbox Backoff Parameters (shows when the mailbox is scheduled to process next time)
postponemailboxprocessinguntil : 07/03/2019 17:01:39
postponesendinguntil : 25/02/2019 18:48:44
receivingpostponeduntil : 07/03/2019 17:00:39
receivingpostponeduntilforact : 01/01/1900 00:00:00
Mailbox Test and Enable Parameters
testemailconfigurationscheduled : False
testemailconfigurationretrycount : 0
testmailboxaccesscompletedon : 25/02/2019 18:48:50
postponetestemailconfigurationuntil : 25/02/2019 18:53:50
Mailbox Last Sync Cycle Information
lastsuccessfulsynccompletedon : 07/03/2019 16:56:39
lastsyncerror: Null
lastsyncerrorcode: Null
lastsyncerrorcount : 0
lastsyncerroroccurredon : 07/03/2019 10:11:30
lastsyncerrormachinename: Null
itemsprocessedforlastsync : 0
itemsfailedforlastsync : 0
Email Server Profile Details
Email Server Profile General Settings (servertype: 1 is others, 0 is Exchange)
servertype : 1
useautodiscover : False
maxconcurrentconnections : 10
minpollingintervalinminutes : 5
Email Server Profile Incoming Email Settings
incomingauthenticationprotocol : AutoDetect
incomingcredentialretrieval : UserSpecified
incominguseimpersonation : False
incomingusessl : True
incomingportnumber : 995
Email Server Profile Outgoing Email Settings
outgoingauthenticationprotocol : Basic
outgoingcredentialretrieval : UserSpecified
outgoinguseimpersonation : False
outgoingusessl : True
outgoingportnumber : 587
Recent Trace Log details
tracecode : 2
machinename : zxxxxx
errortypedisplay : UnknownIncomingEmailIntegrationError
errordetails: Null
collationlevel : 0
modifiedon : 07/03/2019 10:11:30