First of all this is huge number of recipients in your email and it is going to consume time. Can you please try using latest Aspose.Email 20.6 on your end and in case you still feel the performance issue then share the following information:
1: JDK and Operating System Information
2: Source PST
3: Working sample code
4: Statistics of slow performance
But another point is, we have a different version of our product where we use older Aspose version 16.11.0 and there we are not observing this slowness for same type of data. Was there any change in the above APIs ?
I have tried with 20.6 version. The performance is same, no improvement i could see.
While I am working on sample code can you provide little more details on the API.
You have mentioned 15K is huge number.
What is the ideal number library is capable of handling?
Is there any performance bench marking?
Hopefully, you must have received the response by now in paid support help desk too.
Can you please elaborate your questions please as I am unable to understand this. If you are asking about how much bigger PST file library can handle. We have tested multiple GBs of PST file and API has performed well.
There is no such known performance constraint on inquired things. If you feel some performance related issue, you can share the previously requested information so that we may verify the same.