Adhoc reports/email notification for ASM web application firewall in case of blocking

You can use the Scheduled reports feature and tick the checkbox "Send the report file via E-Mail as an attachment" and specify the target e-mail addresses in "Target E-Mail Address" field - read the manual here;

https://support.f5.com/kb/en-us/products/big-ip_asm/manuals/product/asm-implementations-12-1-0/13.html

This will only send the email with report on a schedule (e.g. every 6 hours), but it will be in PDF and will have a nice chart, so ideal for managers and network administrators. If you want realtime e-mails (one e-mail message per blocked request) then it is best to configure ASM Logging Profile to send logs to external logging system like Splunk and then have Splunk to send our e-mail alerts (be ready to get thousands of e-mails an hours though - Internet is a nasty place these days with lots of attack traffic!)