Mail addressed to group not sent to recipients in PNAB

I have a user who sent an email from his mail file to a group in our Domino Directory, but it was not delivered to any of the group members who were in his personal address book. He did not receive any NDRs. I’ve checked the mail routing events on his mail server, and there is no sign that the router tried to send to any of the missing people. I’m satisfied that the e-mails did not go astray - they just never got sent.

The group is fairly large (evaluates to a few hundred members), and is built using other groups in the Domino Directory. The deepest level of nesting is four deep (from the top group to the groups with individual users in it).

I’ve looked at the sender’s personal address book, and he does not have ANY groups listed - so I know the problem is not that he was using out-of-date or duplicate groups.

He has about 200 people in his PNAB, of which about 30 people are internal people - none of these received the e-mail. I’m pretty sure he has added them to his PNAB by copying and pasting from the Domino Directory, as the entries are complete with shortnames, public keys, etc. I’ve checked the Person documents in his PNAB, and the only thing that looks slightly odd is that the mail address field does not include our internal domain. ie. it is First Last/OU/O/C and not First Last/OU/O/C@org.

Can anyone offer any suggestions?

thanks in advance

Subject: additional info

Additional info:The e-mail is not a regular mail form (memo, reply, etc.). It is a custom form that has a computed SendTo field, and a SaveOptions field that is set to “0”. There are no other reserved fields. It uses script to mail the doc on the QuerySave event. The actual command is Source.Document.Send (False) where Source has previously been defined as a NotesUIDocument.

I can reproduce this in my own mail file, by changing a mail setting in my office location document. If I have Recipient name lookup set to ‘Exhaustively check all address books’, then any recipients in my address book are skipped. However, if I have Recipient name lookup set to ‘Stop after first match’, then all recipients get it.

Why would checking all address books result in duplicated recipients missing out altogether?