Skip non-outbox msgs in conversation when deleting: Closes bgo#727268
Skip non-outbox msgs in conversation when deleting: Closes bgo#727268

Don't throw an exception if one EmailIdentifier is unrecognized,
simply skip it and delete the ones that are recognized.

tshikaboom/geary,glebihan/geary,tshikaboom/geary,jimbonator/geary,mjog/geary,robol/geary,githubnemo/geary,martinra/geary,robol/geary,emersion/geary,aatishnn/geary,AtticHacker/geary,glebihan/geary,robol/geary,MohamedIM/geary-unofficial,aatishnn/geary,emersion/geary,rschroll/geary,rschroll/geary,martinra/geary,aatishnn/geary,mjog/geary,githubnemo/geary,jimbonator/geary,AtticHacker/geary,emersion/geary,githubnemo/geary,mjog/geary,glebihan/geary,mpdeimos/geary,jimbonator/geary,martinra/geary,tshikaboom/geary,AtticHacker/geary,geekvigilante/geary