My understanding of the two is that one (msmapi.mapisession) is an activex built on MAPI. The other (mapi.session) is accessing MAPI directly. Although it is not 100% clear. If you look at the site www.codlive.com (http://www.cdolive.com/kb.htm) (which refers to CDO1.x) every piece of code there uses mapi.session. So technically CDO1.x also uses mapi directly. As to why the e-mails aren't being sent? I have found that under certain conditions the direct use of mapi (or CDO1.x or even CDO2.x), unless you program for it, does not have an automatic error return, that could indicate where there is a problem. It could be an authentification issue, or a time-out issue or an unrecoginized user name, or a configuration that is not compatible with what you are trying to do. I would seem to me your best option would be to work with what works on all system, which seem to be msmapi.mapisession.
I have being investigating this issues over the last few years, and recently I have decided that there isn't a single method that works correctly under all conditions, so I decided to creat my own DLL's using Winsock through API calls, as I need to also download the messages via POP3, where most solutions available only send messages.
I am sorry I cannot provide with a clearer solution for your problem.



>Hi Mike,
> SESSION=CREATEOBJECT('msmapi.mapisession') seems to work on all our PCs
>
> SESSION=CREATEOBJECT('mapi.session') seems to only work on some (mine and my testers of course)
>
>I just added some funtionality to our system using "mapi.session" and have it working on several PCs but several users report they cannot send email within the form I added this to.
>
>I could change to msmapi but I don't know why I would have to. Also not sure if the current code (working with mapi) will still work with msmapi (the mail part of the code anyway).
>
>Any thoughts on this would help.
>Thanks