exm error pauses the sending of letters

Question

Sitecore 8.2 update 7, Exm 3.5

In the EDS log we see this:

MessageTaskRunner worker thread 4 11:10:59 ERROR SendEmailError: ChilkatLog:
SendEmail:
DllDate: Aug 31 2017
ChilkatVersion: 9.5.0.69
UnlockPrefix: SITECO.EMX082018
Architecture: Little Endian; 64-bit
Language: .NET 4.5 / x64
VerboseLogging: 0
sendEmailInner:
  renderToMime:
    createEmailForSending:
      Auto-generating Message-ID
      cloneWithReplacements:
        Replacing [-1123963804] with [cid:CID-33dbc438-3df6-4f28-bebd-493db5d47ac3@SITECORECM]
      --cloneWithReplacements
    --createEmailForSending
    renderToMime: Elapsed time: 0 millisec
  --renderToMime
  sendMimeInner:
    progressTotal: 69483
    ensureSmtpSession:
      ensureSmtpConnection:
        SmtpHost: 10.6.90.112
        SmtpPort: 25
        SmtpUsername: Anonymous
        SmtpSsl: 0
        StartTLS: 0
        smtpConnect:
          smtpHostname: 10.6.90.112
          smtpPort: 25
          connectionIsReady:
            Need new SMTP connection
          --connectionIsReady
          smtpSocketConnect:
            socket2Connect:
              connect2:
                ConnectFailReason: Connection rejected
                A few possible causes for a connection being rejected are:
                - A firewall (software or hardware), such as Windows Firewall, is blocking the connection .
                - Nothing is listening at the remote host:port
              --connect2
            --socket2Connect
            Failed to connect to SMTP server..
          --smtpSocketConnect
        --smtpConnect
      --ensureSmtpConnection
    --ensureSmtpSession
  --sendMimeInner
--sendEmailInner
Failed.
--SendEmail
--ChilkatLog

Answer 1

The error you are seeing is expected, as is the email campaign dispatch being paused.

In your case the error is:

ConnectFailReason: Connection rejected A few possible causes for a connection being rejected are: - A firewall (software or hardware), such as Windows Firewall, is blocking the connection . - Nothing is listening at the remote host:port

In other words, Sitecore/EXM cannot connect to your SMTP server. I would suggest you try and set the configuration settings NumberThreads and maxPoolSize to the same value.

The error handling varies dependending on the version of EXM, and the type of error.

SMTP connectivity issues

If connection to the SMTP server fails, the connection will be retried a set number (3 if I recall correctly) of times. If it is not a transient error, the dispatch will be paused. This is handled in a similar way for all versions of EXM.

This error may simply occur because of connectivity errors, but it can also be caused by misconfiguration - specifically the NumberThreads and maxPoolSize setting.

There is no out-of-the-box functionality to automatically resume paused dispatches, but it is possible to create e.g. a custom Sitecore job that will resume any paused dispatches.

EXM 3.0 -> 3.4.2

If the email campaign cannot be dispatched to certain contacts, for example because their email address could not be validated, the email campaign will never move into the "Sent" state. All contacts will be processed, but it will remain in the "Paused" state. I believe the reasoning was that this would allow the user to fix any invalid contacts, and then resume the email campaign.

EXM 3.5+

In later versions of EXM, the email campaign will move to the "Sent" state, even if there are contacts which could not be processed. For each of those contacts an interaction will be created with a "Dispatch failed" event describing the reason. You can see the list of failures on the campaign report page.