One DAG member not sending emails


  • Hi guys,

    I recently 'adopted' a half migrated exchange 2013 environment, consisting of a CAS server and two mailbox servers in a DAG. At the moment all databases are running in Server1 because Server2 refuses to send email. I created a new test database and in it a test account. It can receive email, but emails sent by the test mailbox remain in the Outbox. Moving the mailbox or database to Server1 results in emptying of the Outbox.

    I've checked the ComponentState, all active, checked if Server2 is allowed to send in the send connector (even removed and added it again). Firewall is turned off and antivirus uninstalled. Installed CU15 yesterday on Server2.

    I even recreated several connectors, since the previous admins played around with them.

    Both servers have these Receive Connectors:

    - Client Proxy port 465 on both IPv4 and IPv6

    - Default ServerName port 25 on IPv4

    - Gateway SMTP Relay from 2 remote servers over port 25 with the IPv4 IP address of the local server

    - Internal Relay for MFD's over port 25 with the IPv4 IP address of the local server.

    The lack of error messages likely means it is working as configured, so I'm strongly suspecting a setting I'm overlooking, or a connector (2525?) that should be present.

    Does anyone have any idea where to look?

    Thanks for your help!


    Friday, March 17, 2017 7:38 AM

All replies

  • Receive connectors aren't used by clients for sending mail (except for POP and IMAP clients, which send via SMTP), so you can stop looking there.

    Are all the services running?  Is there anything in the event log?

    Have you tried rebooting the server?  It's amazing how often that fixes things.

    Is this problem repeatable across multiple clients and mailboxes?  If not, maybe it's the client.  Make sure that there aren't any add-ins enabled during testing.

    What cumulative update are you at?

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!

    Saturday, March 18, 2017 2:16 AM
  • Hi,

    How's this issue going on with Ed's suggestion?

    If this issue also occurs on local mail flow, please double check the free disk for mailbox database.
    Get-MailboxServer | Get-MailboxDatabase | fl Name,Server,EdbfilePath,LogFolderPath
    I experience a similar issue, the message stuck in Outbox, and it turns out that the disk is full.

    Meanwhile, if this issue only occurs on outbound mail flow, run "Get-SendConnector" to double check the value of SourceTransportServers setting for send connector.

    Best Regards,

    Allen Wang

    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Monday, March 20, 2017 6:42 AM
  • Hi Ed,

    thanks for your reply! Yes I rebooted the machine on several occasions (usually not necessary), especially after upgrading to CU15, to rule out a bug. I have tried this with different databases and different mailboxes.

    As soon as a mailbox is on Server1 it is allowed to send, but when on Server2 it isn't.

    In OWA it shows the message "You don't have permission to perform this action."

    And messages remain in either the Drafts or Outbox folder.

    I also checked the databases, the disks still show plenty of space. This Test database was newly created.


    Monday, March 20, 2017 8:44 AM
  • Hello,

    Sorry for delay.

    Base on my research, please try to put Server2 into Maintenance mode, then put it back for testing. More details, refer to: Exchange 2013 Maintenance mode.

    Meanwhile, since those message stuck in Outbox, it seems something wrong during submission. Thus, enable protocol log for the intra-organization Send connector in the Mailbox Transport Submission service on Mailbox servers:
    Get-TransportService | Set-TransportService -IntraOrgConnectorProtocolLoggingLevel verbose
    Open Log location (default location:  %ExchangeInstallPath%TransportRoles\Logs\Mailbox\ProtocolLog\SmtpSend\Submission), find this problematic event and analyze this log file.

    Best Regards,

    Allen Wang

    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Wednesday, March 22, 2017 3:01 AM
  • Here's a health submission log for example (with my annotation):
    2017-03-03T02:27:37.820Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,0,,,*,,attempting to connect
    <start communication> 2017-03-03T02:27:37.820Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,1,,,+,,   
    2017-03-03T02:27:37.820Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,2,,,<,"220 Microsoft ESMTP MAIL Service ready at Fri, 3 Mar 2017 10:27:37 +0800",
    2017-03-03T02:27:37.820Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,3,,,>,EHLO,
    2017-03-03T02:27:37.820Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,5,,,>,X-ANONYMOUSTLS,
    2017-03-03T02:27:37.820Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,6,,,<,220 2.0.0 SMTP server ready,
    2017-03-03T02:27:37.825Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,7,,,*, CN=EXC2016 CN=EXC2016 226C045186D8E2A64C9E58F48E5E3E88 F527D496DE39B8EECE49738782A566E1C0CA98B4 EXC2016;,Remote certificate Certificate subject Certificate issuer name Certificate serial number Certificate thumbprint Certificate subject alternate names
    2017-03-03T02:27:37.825Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,8,,,*,,"TLS protocol SP_PROT_TLS1_2_CLIENT negotiation succeeded using bulk encryption algorithm CALG_AES_256 with strength 256 bits, MAC hash algorithm CALG_SHA_384 with strength 384 bits and key exchange algorithm CALG_ECDH_EPHEM with strength 384 bits"
    2017-03-03T02:27:37.825Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,9,,,*,F527D496DE39B8EECE49738782A566E1C0CA98B4,Received certificate Certificate thumbprint
    2017-03-03T02:27:37.825Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,10,,,>,EHLO,
    2017-03-03T02:27:37.825Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,12,,,>,X-EXPS EXCHANGEAUTH SHA256 ,
    2017-03-03T02:27:37.825Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,13,,,>,<Binary Data>,
    2017-03-03T02:27:37.828Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,14,,,<,235 <authentication information>,
    2017-03-03T02:27:37.828Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,15,,,*,SMTPSendEXCH50 SendRoutingHeaders SendForestHeaders SendOrganizationHeaders SMTPSendXShadow,Set Session Permissions
    <Mail From> 2017-03-03T02:27:37.828Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,16,,,*,,sending message with RecordId 245 and InternetMessageId <>
    2017-03-03T02:27:37.828Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,17,,,>,"MAIL FROM:<> SIZE=0 BODY=BINARYMIME XMESSAGECONTEXT=ADRC-,EPROP-", 
    <Mail To> 2017-03-03T02:27:37.828Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,18,,,>,RCPT TO:<>, 
    <Check Sender> 2017-03-03T02:27:37.832Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,19,,,<,250 2.1.0 Sender OK, 
    <Check Recipient> 2017-03-03T02:27:37.832Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,20,,,<,250 2.1.5 Recipient OK, 
    2017-03-03T02:27:37.832Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,21,,,*,,Transferring 2 resolved and 0 unresolved recipient(s) (402 total properties in 12549 bytes)
    2017-03-03T02:27:37.832Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,22,,,>,BDAT 12571,
    2017-03-03T02:27:37.832Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,23,,,*,,Sending blob ADRC-
    2017-03-03T02:27:37.836Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,24,,,<,"250 2.6.0 CHUNK received OK, 12571 octets",
    2017-03-03T02:27:37.836Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,25,,,*,,Transferring 7 mailitemlevel and 3 recipient level properties for recipient(s)
    2017-03-03T02:27:37.836Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,26,,,>,BDAT 641,
    2017-03-03T02:27:37.836Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,27,,,*,,Sending blob EPROP-
    2017-03-03T02:27:37.836Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,28,,,<,"250 2.6.0 CHUNK received OK, 641 octets",
    2017-03-03T02:27:37.840Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,29,,,>,BDAT 6035 LAST,
    <Submission success, then move message to Queue to deliver> 2017-03-03T02:27:37.959Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,30,,,<,"250 2.6.0 <> [InternalId=11712375816209,] 6441 bytes in 0.118, 53.279 KB/sec Queued mail for delivery",  
    <Quit Communication> 2017-03-03T02:27:37.959Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,31,,,>,QUIT, 
    2017-03-03T02:27:37.959Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,32,,,<,221 2.0.0 Service closing transmission channel,
    <Close Communication> 2017-03-03T02:27:37.959Z,Mailbox Proxy Send Connector,08D4612FA4E74A6D,33,,,-,,Local 

    Best Regards,

    Allen Wang

    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Wednesday, March 22, 2017 3:03 AM
  • Hello,

    Any updates and more information in submission log for  further troubleshooting?

    Best Regards,

    Allen Wang

    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Monday, March 27, 2017 6:03 AM
  • Hi Allen,

    thanks for your responses! I've been flat out resolving issues, so sorry for the delay!

    At some point I found a log in the SMTPSend that showed a send connector simply disconnecting and not sending the contents of the mail, no error message. At that point the company had been suffering too much due to disrupted mailflow, so I decided to take Server2 out of the DAG and remove the DAG altogether. It took too much time to search for that needle in the haystack. I may try it again in the near future, when all the issues have settled down and the company has experienced a moment of peace and quiet ;-). Thanks again for your support!


    Tuesday, April 4, 2017 3:09 AM
  • Well, thanks for your update and efforts.
    If you get any update and need further assistance, please be free to contact us.

    Also, help to mark the useful reply as answer, thanks again for your cooperation.

    Best Regards,

    Allen Wang

    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Wednesday, April 5, 2017 2:22 AM