One of our users clicked "unsubscribe" on a Maniphest task and got the following error message:
```
Notice: Undefined index: HTTP_REFERER in /opt/sendgrid/site/releases/80dcee6f57f4346abe4744a3aa2fda2f8719f320/web/standalone.php on line 389
Unsubscribe successful
Your email XXXX@signifyd.com has been successfully unsubscribed from this list!
```
But he continued to receive email alerts for the task. So he went back and clicked the button again and got the same error message. Now he's not getting **any** email alerts for anything. I checked and his email preferences have email turned on for everything. Even went into the DB and copied my preferences over his, since I am getting emails:
```
set @v1 := (select user_preferences.preferences from user_preferences, user where userPHID=phid and userName = 'oliver');
update user_preferences set preferences=@v1 where userPHID = 'HIS-PHID';
```
I then verified both in the web gui and in the DB that my settings had been applied. However, he's still not getting emails. We double-checked his spam folder and I ran `./bin/mail list-outbound` and `./bin/mail show-outbound` and mail seems to think that it is delivering the messages, but they simply don't arrive any more.