Email send out fails due to the maximum number of concurrent connections on SMTP server.

[Stellan_Ronnkvist]

Hi all,

I have a problem for one of our customers that not all emails are sent out from Qlik NPrinting April 2019 due to the limitation of connections to the SMTP server.

The error says: Failed to send e-mail for bucket 28e41438-b123-4e36-b843-51be5188d34a to name.lastname@company.com. ERROR: 4.3.2 The maximum number of concurrent connections has exceeded a limit, closing transmission channel

For some of the groups in Qlik NPrinting we have about 200 recipients. The size of the email is less than 1 MB since it contains of a couple of html pictures and one PowerPoint report.

We are using the API to start the publish task from a QlikView application. I tried with the Sleep() command between each call to the task ID in Qlik NPrinting but that had obviously no effect since it's not the number of tasks that is the problem, it's the number of recipients in each group that is.

I have asked the IT support to increase the limit of concurrent connections on the SMTP server from the default value of 20 to 500 but they didn't approve since it might interfere with their Spam policy on the servers, which I can understand.

An "easy" solution is to divide the recipients into smaller groups but since the customer updates the groups on regular basis I don't know if that would work in the long run.

One final note; we did not have this problem when we used the Qlik NPrinting September 2018. I don't know if something has changed regarding emails and SMTP between the different versions. 

Has anyone out there experienced similar problem?

Best regards,
Stellan Rönnkvist
Stockholm

[Ruggero_Piccoli]

Hi,

Maybe the SMTP administrator can change the limit only for the Qlik NPrinting user or IP address so other users cannot use this rule for spamming. 

In the Qlik NPrinting side, at the moment (June 2019), there are not configurable parameters to limit the number of opened connections.

Another workaround could be to split the sending into different publish task.

Please open a support ticket with a link to this conversation. Thanks.

Best Regards,

Ruggero

[KHSDM]

Hi Stellan,
Did you manage to solve this problem? I'm also in the same situation, where some email failed to send due to exceeded connection. And we can't increase the limit too.

[Ruggero_Piccoli]

Hi,

There are not parameters to limit the number of SMTP connections on Qlik NPrinting side. You can only work on SMTP server configuration.

A workaround could to split a single task into multiple tasks and schedule them at a different time in order to split the workload for the SMTP server.

Best Regards,

Ruggero

[Stellan_Ronnkvist · Accepted solution]

Hi,

I have tried the following: 

1. Since we are using a QlikView application to trigger the tasks in NPrinting via the API I added a Sleep() command in the load script to add some time between each task execution. (We have nine tasks for this report, one task for each group of recipient.) My idea was to make sure that the tasks wouldn't overlap each other, but unfortunately that didn't work. (Because the recipient groups are to big.)
2. I made a request to the IT department and asked them to increase the limit for concurrent connections and they agreed to increase it from 20 to 100. That change had some effect and the number of errors decreased from ~110 to ~70 for each task.  Some days it was only ~20 errors, but I'm not sure why.
3 Today we have changed the limit to 200 and we will do some tests during the rest of the week. This will hopefully do the trick!

I didn't want to split the recipient groups into smaller groups, that would be too difficult to administrate. But I think if you are not able to change the limit on the server your only option is, as Ruggero also wrote, to add some time between each task execution but also, if you have large recipient groups, divide them into smaller groups. I'm not very fond of that solution but that is your final option.

Best of luck!

/Stellan 

[fabio_ribeiro]

Hi Ruggero, do you know if in actual days have some news about some feature to control a number of SMTP connections?

Yesterday I was confronted about a situation very similar to the one reported here.

[Ruggero_Piccoli]

Hi,

I'm sorry but I don't have any news about this new feature request. I added it in the new ideas public community here https://community.qlik.com/t5/Ideas/Set-the-maximum-number-of-SMTP-connections-in-Qlik-NPrinting/idi...

Best Regards,

Ruggero

[woundine1]

Hi, can you tell me where could you manipulate the  limit for concurrent connections?

please let me know the specific location of configuration file if you can.

it would be greatly appreciated

[Ruggero_Piccoli]

Hi,

It is a SMTP server configuration because you cannot change it on Qlik NPrinting side. So you have to refer to your SMTP documentation or administrator.

Best Regards,

Ruggero