How can you build an internal changelog for deliverability impacts?

You notice inbox placement dip, dig through your notes, and realize you changed your sending frequency three weeks ago. But you can't remember if that was before or after Gmail pushed that filter update. Sound familiar? A deliverability changelog fixes that problem.

The idea is simple. You keep a running log of everything that touches your deliverability, whether that's a provider policy change, an authentication update, a new campaign type, or a sudden bounce spike. When something breaks (or improves), you can trace exactly what happened and when.

What to track in each entry

Every entry in your changelog should answer five questions. What happened? When did it happen? Which providers or sending streams were affected? What metrics shifted? And what did you do about it?

In practice, each row or entry looks something like this:

• Date: When you first noticed or confirmed the change
• Event type: Provider update, internal change, blocklist incident, authentication issue, or campaign-level decision
• Affected provider(s): Gmail, Outlook, Yahoo Mail, or all
• Metrics before and after: Inbox placement rate, bounce rate, complaint rate, delivery lag, open rate per provider
• What you changed: Authentication config, sending volume, list segment, subject line approach, from address
• Outcome: Did placement recover? How long did it take? What worked?
• Source: Where you heard about the provider change (Gmail Postmaster alert, industry blog, your own monitoring)

What counts as a loggable event

Anything that could explain a shift in your metrics deserves an entry. On the provider side, that includes Gmail bulk sender requirement updates, DMARC enforcement changes, Outlook filter behavior changes, and Yahoo authentication requirement rollouts. These are well-documented when they happen, so you won't have to guess.

On your side, log when you add a new sending stream, change your from address, update your SPF or DKIM config, run a re-engagement campaign, or significantly increase send volume. Internal changes cause just as many mystery dips as provider changes do.

How to structure it

A shared spreadsheet works fine to start. One sheet for the log itself, one sheet as a quick-reference summary of your current authentication setup and baseline metrics. Date your baseline row so you always have something to compare against.

So some teams use a project management tool like Notion or Confluence, especially if multiple people are involved in email operations. The format matters less than the habit. If nobody updates it, it's useless.

How to actually use it

The changelog earns its value when something goes wrong. Instead of starting from scratch every time placement drops, you scan back 30 to 60 days and look for overlapping events. You start to see patterns too. Maybe your open rates at Outlook always dip in the two weeks after a volume spike. Maybe Gmail complaint rate creeps up whenever you mail a segment that hasn't opened in 90 days. That kind of pattern is invisible without a record.

It's also useful when placement suddenly shifts and you need to rule out causes fast. You check the log, confirm no internal changes in the last two weeks, and narrow your focus to provider-side behavior. That alone can save hours of guesswork.

If you want a head start on monitoring the provider side, our SOS hotline is free and we're happy to walk through what a good changelog setup looks like for your specific program.