Back in March 2000 I developed a program which uses Extended MAPI to created and send e-mails via Microsoft Outlook. I had some problems creating the RTF format e-mail but fortunately managed to sort it all out with the help of "Neo" among others on this website. The program has since been running perfectly well on the target computer (it was developed for one specific client and has, up to now, been used on just the one computer). However, my client decided to install the system on another computer as well and when he did this it turned out that the Extended MAPI would not function correctly on it! Whenever it reaches the line of code which should create the MAPI.Session object it fails, with the 429 error message! I cannot see why this should be, in fact I have also tried installing the program on three other computers and it produces exactly the same error on all three, yet it is still working perfectly on the original computer on which it was installed! I have checked for files, etc., as I assumed that perhaps a file had become missing or corrupted, but even after replacing all the MAPI files and OLEMSG.DLL, file, etc. with ones from the development machine (on which it also still works fine), it still seems to show the same problem. I am now reaching the point where I will be bald very soon so, if anyone can help I would be extremely grateful. I am prepared to "go back" over everything and perhaps a fresh mind on the subject may point out something which I have missed (which could of course be very simple), so please don't worry about making "basic" suggestions; I will follow them all through. I need someone now with a "detached" view to "direct me". Thanks in anticipation of your assistance!! Cheers.