Move email-sending code into EmailService #1148

Job	Run time
Docker Hub / Release	1m 22s
Staging / Deploy	2m 40s
Staging (WebSocket) / Deploy	2m 35s
Production / Deploy	3m 56s
Production (WebSocket) / Deploy	3m 16s
Production (Canada) / Deploy	3m 55s
	17m 44s

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