Dead letters keep appearing

Symptom: History › Dead letters fills up for a destination, or the Dead letters alert is raised.

Each dead letter has the reason. The common ones:

Reason	Cause	Fix
A refusal status from the destination (A7xx, A9xx, Cxxx)	The destination will not take it: often an unknown SOP class, a missing attribute, or a duplicate it refuses	Check the destination’s log for that instance; adjust the destination, or add tag edits on the destination to fix the header.
refused … in every transfer syntax tried	The destination accepts none of the syntaxes its list offers for this kind of image	Run Test syntaxes; end the list with As received, or add the syntax it wants.
Could not convert … to any transfer syntax	The conversion failed (a 16-bit image to 8-bit JPEG Baseline, say)	Add a lossless syntax or As received after it.
out of attempts	Retryable refusals kept coming	Find why the destination keeps refusing; raise Max attempts only if it is transient.
A script’s rejection	The destination’s script called reject or failed	Fix the script; Test it with a sample header.
De-identification refused it	Burned-in annotation without a mask rule	Add a mask rule for that device, or allow it in the profile.

After fixing the cause

Select the dead letters and Re-queue them: they go to the same destination again. Send sends them to another destination or group instead; Purge deletes them; Download gives you one to examine. Dead letters are kept for Dead-letter retention (days) (Settings), then deleted.