w3wp crashes when using ChilkatAx-9.5.0 Email with Async method

I am using ChilkatAx-9.5.0 on windows 2012, in 32bit mode, to send email to my customers i am using the ASYNC method (Set task = mailman.SendEmailAsync(email)) few seconds after sending the mails, the w3wp crashes

Faulting application name: w3wp.exe, version: 8.5.9600.16384, time stamp: 0x52157ba0
Faulting module name: ChilkatAx-9.5.0-win32.dll_unloaded, version: 9.5.0.80, time stamp: 0x5db71809
Exception code: 0xc0000005
Fault offset: 0x005509b6
Faulting process id: 0xf20
Faulting application start time: 0x01d62ec6ab20d2ca
Faulting application path: C:\Windows\SysWOW64\inetsrv\w3wp.exe
Faulting module path: ChilkatAx-9.5.0-win32.dll
Report Id: 9bf35f6d-9aba-11ea-80ca-00155d7f720a
Faulting package full name: 
Faulting package-relative application ID: 

Fault bucket , type 0
Event Name: BEX
Response: Not available
Cab Id: 0

Problem signature:
P1: w3wp.exe
P2: 8.5.9600.16384
P3: 52157ba0
P4: ChilkatAx-9.5.0-win32.dll_unloaded
P5: 9.5.0.80
P6: 5db71809
P7: 005509b6
P8: c0000005
P9: 00000008
P10: 

Attached files:

These files may be available here:
C:\ProgramData\Microsoft\Windows\WER\ReportQueue\AppCrash_w3wp.exe_d0f817ab215bfa2edbb9f26b9ed82f507ef4b26c_234314c6_12e2e666

Analysis symbol: 
Rechecking for solution: 0
Report Id: 9bf35f6d-9aba-11ea-80ca-00155d7f720a
Report Status: 4100
Hashed bucket: 

Note that the emails are sent correctly, but few seconds later IIS crashes

I don't have this problem when using the classic method, i have it only with the async method

please advise on how to fix this cheers mike