Are some users experiencing the 64-limit error when sending mail to group(s) containing a large number of members, where as other people don't encounter the same problem mailing the same group (listed in the Domino Directory). Quite possibly these problematic users have a copy of this group locally or may have a local copy of the Domino Directory.
The problem resides in the way that the Notes Client tries to handle groups listed in the SendTo (and similar) field upon the sending of mails. The Notes Client initially tries to locate this group locally, if unsuccessful thereafter in the server's Domino Directory (depending on the user's settings in their current location document). If this group is first encountered locally then the Notes Client tries to expand the group on the mail to list all its associated members in the SendTo field. Thus, resulting in the error above. If the group is not encountered locally (but is listed in the Domino Directory), the Notes Client does not expand the group immediately upon dispatch.
It may be desireable to continue having this large group type locally but to mimic it non-immediate expansion when using in mails. This is achieved by the below code, which can be applied via a SmartIcon (as opposed to altering the MEMO form on the server's mail template). The code tags the mail not to expand the group until the mail hits the router, where upon it is then safely expanded.
FIELD $ExpandGroups := $ExpandGroups;
@If( @IsDocBeingEdited & ( @Contains( @UpperCase( Form ); "MEMO" ) | @Contains( @UpperCase( Form ); "REPLY" ) ); @Do( @SetField( "$ExpandGroups"; "0" ); @Prompt( [OK]; "Mail to large group(s) notification"; "This mail has been configured to dispatch to extra large group listings." ) ); @True )
NB: The above code ensures that the '$ExpandGroups' field is not set unless the current form is in Edit mode and is of a Memo/Reply variety. If these conditions are met then the code prompts the user of a successful tagging. Please adjust code according to your needs/requirements.