You could use a centralized e-mail handler (IE: https://portal.blueprism.com/products/vbos/centralised-email-manager ), then have it dump into a queue that the process occasionally monitors. Since BP does not support multi-threading, you could probably trigger it by pushing some SQL queries to the database.
Alternatively, you can have a process that just checks e-mail when it runs. I've seen this done either in specified windows, or as a 24/7 process on a dedicated VM.
E-Mail found?
-Yes - Do logic
-No - Wait a while and check again
As for checking for a specific subject, this can also be done in a multitude of ways. The simplest would be to set up an Outlook rule to dump it into a specific inbox subfolder that the bot monitors. If you're using OOB mail solutions in BP 5x or earlier, you could also check the subject for each message you loop through. If you're in BP6x, the Outlook object has some built-in filtering to only check for specific subjects.
Tons of ways you could go about it, it just depends on your personal preferences.
