[Task]: send alert when socklabs fails to send an email

[eviljeff]

Description

We rely on emails for important communication to users, but there are failure cases where the information about the failure could be hidden, or we don't check for it.

For example:

• The initial connection to Socketlabs could fail. The exception in the task would lead to a traceback in Sentry but, unless there is a repeated outage, wouldn't alert us
• Socketlabs could receive our payload, but fail to send the email.

Note, we probably don't want to alert for every single email failure, and for every type of email. More specification is needed.

Acceptance Criteria

• An alert is sent when an important email is not sent

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