Burrow 1.0 RC configuration for a large amount of email addresses? address+consumer_group@domain.com

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In pre 1.0 I could create an email notifier that included the consumer_group in the address like.

`email+consumer_group@domain.com` I can still do this but:

A lot of configuration is repeated. SMTP information feels like it could be constant and would be nice to just reference in an [smtp.name1] section and just refer to in a notifier though. Some psuedo-code:

`for consumer_group in consumer_groups:`
```
[notifier.email_{{ consumer_group }}]
class-name="email"
extras={key="value", key2="value2"}
interval=300
group-whitelist='*'
threshold=1
template-open="{{ burrow.email.template }}"
template-close="{{ burrow.email.template }}"
send-close=true
server={{ burrow.email.server }}
port={{ burrow.email.port }}
auth-type=plain
username={{ burrow.email.username }}
from="burrow-beta-noreply@domain.com"
to="me+{{ consumer_group }} @domain"
password={{ burrow.email.password }}
```
`end for`

Something like this, or along the same lines, (I'm not married to this config line for line). For instnace, maybe even the template, threshold, send-close, and extras could be moved into their own sections and merged with a notifier section?
```
[smtp.config1]
server={{ burrow.email.server }}
port={{ burrow.email.port }}
auth-type=plain
username={{ burrow.email.username }}
from="burrow-beta-noreply@domain.com"
to="me+{{ consumer_group }}@domain"
password={{ burrow.email.password }}
```
`for consumer_group in consumer_groups:`
```
[notifier.email_{{ consumer_group }}]
class-name="email"
extras={key="value", key2="value2"}
interval=300
group-whitelist="*"
threshold=1
template-open="{{ burrow.email.template }}"
template-close="{{ burrow.email.template }}"
send-close=true
smtp="smtp.config1"

```
`end for`

Start by tracing Burrow's existing email notifier and configuration handling. Compare the current notifier settings with the proposed reusable SMTP section and per-consumer-group address expansion; done should be defined as an agreed configuration design that avoids repeated SMTP and notifier settings.

Written by the indexing model from the issue text.