I read that I cannot use an address to send a message with an SMTP server from a different ISP. However I migrated from an Outlook Express application under Windows XP. It used to work with two different ISP's, viz Orange and Free. I could send messages from james.aiche@free.fr through smtp.orange.fr and vice versa. I migrated my application to Thunderbird then to a new computer under windows 8.1 and it worked with my Orange Livebox (Orange ISP) for sending messages from either james.aiche@orange.fr or james.aiche@free.fr. However I screwed it up when I moved to another location and used a freebox from the french FREE ISP. changed the server to smtp.free.fr in all accounts but then it would not work. The outgoing server would not accept my messages. Does anybody know a way around this problem? Thanks a lot and best regards James Aiche