Hello Dear,

Hope You could help me with understanding of cooperation with Exchange 2013 server.

Now we are using Blackpearl 4.6.11 version with just sending e-mails to Exchange 2013 server via K2 smtp module.

We have configured smtp-server name, 25 port, from address, without using TLS encription, like it described here: link

When Exchange server is healthy, all works just fine!

But recently we have problems, when Exchange has large queve of undelivered e-mails (due to problems with Exchange DBs) our K2 notifications are delivered with a large delay (could be 30 min or couple of hours).

On the K2 server side we see such exceptions for attempts of sending e-mails:

"System.Net.Mail.SmtpException: Insufficient system storage. The server response was: 4.3.1 Insufficient system resources"

and

"System.Net.Mail.SmtpException: The operation has timed out."

Due to such exceptions our instance returns error and stops.

The question is - how K2 smtp module exactly works? How many attempts it will use for sending e-mail? What exact timeout will return an error in instance?

We need to understand in what cases exactly we will receive error with instance flow due to exchange problems.

For example, we have done an experiment when e-mail destination mailbox will be full.

In such case we see smtp exception in logs like: "System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable. The server response was: 5.7.1 Unable to relay"

but instance continue to work according to flow without errors.

Please, help to understand in what cases instance will be stopped with error due to smtp exception?

We need it to understand how can we modify configuration on K2 server and exchange to exclude such instance errors due to exchange problems.