WE HAVE MITCHELL AND WE SEND EMAILS WITH THUNDERBIRD BUT WONT WORK

Ok, this is a forum, there is no telephone support, so you will need to take the time to acually describe your problem. If you want folk to read it use the cap lock key on the keyboard. this is making my eyes bleed trying to read it. I assume by mitchell you mean . https://www.mitchell.com/ (I got that from google in an attempt to try and understand) Now to make any progress you are going to have to provider the error you are getting. We can not see them. I am assuming a lot here, but I think that your software sends out quotes and invoices using an email address and it has stopped working of late. but that is about where I get lost. I think it is probably using one of two technologies. MAPI or mailto: both get the job done but the types of errors are very different. So what are the error messages actually saying? (verbatim please as minor details can be important)