can't send from louise@lastresearchandediting.com

I am not able to use my Thunderbird account to send via my louise@lastresearchandediting.com e-mail address. I have been trying to get this resolved with Thunderbird's help. This is what that person said. "Ok, it seems the issue is not the SMTP server, but the DKIM and SPF settings on server. Most users ask their email provider to make that correction." Please help.