The current size of the field that holds the e-mail addresses in a log is not enough to hold all the e-mail addresses.
As a result the "recipients" field sent from in.emaild.smtp process is cut off at some random location by the infrastructure (the location is not related to e-mail address structure). On a later stage, list of e-mails is sorted, and the triuncated e-mail moves to some place in the middle of this list.