This is the reference for the email metrics you will see in Bookboost's campaign reports: what each one counts, and what it tells you when it moves. Use it alongside the Journey and Broadcast reports rather than on its own.

The total number of emails dispatched.

On its own it only tells you the scale of the send. It is most useful as the denominator: a low ratio of opens or clicks to Sent points at list quality or at the campaign not being relevant to who received it.

The number of distinct recipients who opened the email. One guest counts once, however many times they open it.

Opens are the first sign of engagement, and they respond mostly to the subject line and the send time. Compare open rates across subject lines and times of day to see what your guests actually respond to.

Emails that could not be delivered at all.

A rising Failed count is a data-quality signal rather than a content one. Look at where those guest records came from before you look at the campaign.

Emails that are temporarily undeliverable, for example because the inbox is full or the receiving server had a problem.

A soft bounce is not a broken address. If the same address soft-bounces repeatedly across campaigns, it is worth checking, but a one-off is normal. This also appears as Soft bounce rate, a percentage of messages sent, in the deliverability row on the Marketing Dashboard.

Emails permanently rejected, either because the address does not exist or because the receiving server has blocked delivery.

Hard bounces are the ones that damage your sender reputation, which in turn affects deliverability for every other guest. Bookboost excludes an address from future sends automatically once it has hard-bounced twice, so persistent hard bounces taper off on their own. Treat a sudden spike as a sign of a bad import or a broken signup form rather than something to clean up by hand. See Automatic exclusion of hard-bounced email addresses. This also appears as Hard bounce rate, a percentage of messages sent, in the deliverability row on the Marketing Dashboard.

The number of recipients who marked the message as spam or junk in their mail client, rather than unsubscribing. It is recorded against the campaign that sent the message.

Complaint rate is the deliverability signal to watch above the others. Mailbox providers start throttling a sender once complaints reach around 0.1% of a send, and stop delivering almost entirely around 0.3%. A rising Marked Spam figure is often the earliest sign that a mailbox provider is losing trust in your sending domain, ahead of any change in your other numbers.

Complaint volumes are naturally small: often zero or one per domain per month, even for a high-volume sender. Treat a non-zero reading as worth investigating, not as a list to clean up by hand. Unlike Hard bounces, addresses that complain are not currently removed from future sends automatically. This also appears as Marked spam rate, a percentage of messages sent, in the deliverability row on the Marketing Dashboard.

The number of distinct recipients who clicked at least one link. One guest counts once.

Clicks are the most direct measure of whether the content did its job. Look at which links and calls to action get clicked, not just the total.

The percentage of recipients who clicked a link in the email.

CTR is the number to compare between campaigns, because it is independent of audience size. Comparing it across formats and offers tells you what drives action.

The number of recipients who opted out after receiving the email.

A rising unsubscribe rate usually means one of two things: the content is not relevant to the people receiving it, or you are sending too often. Both are fixable by narrowing the audience rather than by rewriting the email.

See Broadcast reports and Journey reports for where these metrics appear, and Reports overview for how much of your database is reachable in the first place.

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