I was curious about this so I hit the 'Log A Call Button' in my dev org and ran a SOQL query to see if any fields had data to tell us it was a call other than the Subject line and found the TaskSubtype field had been updated by the system with the value of 'call'. I checked in reports and it is a field you can filter on.
I faced totally same problem.
In my case, I contacted SendGrid support and asked to activate my SendGrid account.
In two working days, they reactivated my account with their apology.
And now my app successfully send email.
Please try this. Good luck.
Here is SendGrid support:
I am going to assume that CaseNumber and CaseHistory are stored as measures. If they are stored as strings you can convert them to numbers using the string_to_number function.
What might work for you is to create a string version of the case number which can be used as a partition to find the max of the case history variable. Then you can use a filter to ...
Jonathan, when you add the send grid add on to Heroku, it creates two environment/config variables.
I suggest that you go to this URL https://app.sendgrid.com/login and try to log in with these credentials.
Your account might be locked because you did not verify your email at sendgrid end, which a required step. Once you do that it should be work.