When Active/Standby failover send mail

If you tested the SMTP email is working and configured for your feature then maybe see /config/user_alert.conf as this is the only file that you should touch for custom alerts. (https://support.f5.com/csp/article/K30371285 ).

Other usefull links:

https://support.f5.com/csp/article/K54018808

https://support.f5.com/csp/article/K87630102

https://support.f5.com/csp/article/K2446

Also you can create a bash script that triggers the "logger -p " command and add a message to /var/log/ltm (https://support.f5.com/csp/article/K11127 ) and place the script as You can even trigger scripts on the F5 device if the state changes from active to standby or from standby to active by adding the scripts under /config/failover/. For example if you have a bug for a critical process that causes a failover ( you can use the command show /sys ha-status all-properties to check for this https://support.f5.com/csp/article/K20060182 ) but the device does not reboot or fix the process you can run a script to when the device becomes standby to restart the process. (https://support.f5.com/csp/article/K6008 )

An article I made about this long ago:

https://community.f5.com/t5/codeshare/knowledge-sharing-ways-to-trigger-and-schedule-scripts-on-the-f5/ta-p/291469