Boulder: dedup emails of multiple certificates by the same reg id in any given run of expiration mailer

[jmhodges]

This would cause at least a 20% email reduction because we currently have 20% all-domains-equal duplicate certs. These were typically done very close in time with the le client (and the same would likely happen for CDN-style overlapping certs). It's likely a larger reduction when we account for folks adding additional SAN entries soon after another issuance.

[jmhodges]

Putting this in the current sprint because it's less effort and will cover most of the current cases in https://github.com/letsencrypt/boulder/issues/1346

[jmhodges]

(We talked about doing this as a team after a long design discussion between myself, @jsha, and @rolandshoemaker.)

[ZlatyChlapec]

Moved to #1396

[jmhodges]

This isn't an appropriate ticket for that discussion. Please make a new one.

[tomchiverton]

I assume this is closed, but not yet deployed as I got an email this morning about a domain that has valid later certificates.
What's the timeline for deployment ?

[Zenconomy]

I also keep getting renewal emails for domains that have already been renewed.... got one today.