Every message the platform sends is logged, whether it succeeded or failed.
The principle
A failed email never fails the action. If the allotment email bounces, the delegate is still allotted. The failure is recorded with its error and can be resent.
This is deliberate: an email provider having a bad minute should not stop a conference running. It does mean nobody finds out about failures unless somebody looks.
Where failures surface
On the admin overview, as a card showing the eight most recent failures. Check it daily; it is there so you do not have to go looking.
On the delegate, in the drawer at the registrations desk, which lists every message sent to that person with its outcome.
Resending
From the delegate drawer, against the specific failed message. This is the fix for "I never got my allotment email" and it takes about five seconds.
The messages
Delegates get: registration received, co-delegate registered, allotment, co-delegate notice, payment confirmed, payment reminder. Writers get the three review outcomes. Staff get the invite. Anyone can get a magic link. Recruitment sends selection emails.
Delegate-facing detail is in emails you will receive, which is worth reading so you know what your delegates have been told.
Why an email fails
In rough order of frequency: a typo in the address, an institutional mail server rejecting it, a full mailbox, and provider problems. The recorded error usually says which.
A typo is fixable: correct the address on the delegate record, then resend.
Staging
On a preview deployment every outgoing message is redirected to a single address and its subject is prefixed to make that obvious. If you are testing and the delegate did not get their mail, check whether you were on staging.