Outlook 2010 Attachment issue

HI,

In one of our VP using Outlook 2010 with IMAP settings, While reciveing mail with attachments from another user who is having pop3 settings in their outlook 2007 or 2010.

Issue is that our VP reciveing 4 attachments instead of 2 (which is duplicate attachments of other 2, Not original other 2 attachments) & While sending also same but if he sends 4 attachments other person recives only 2 instead of 4.

Can any one suggest to fix the issue!!!!!!!!!!!

Thanks in advance