Yahoo unblocked - hurrah

Finally, at the second time of jumping through all Yahoo's hoops, I got some at Yahoo that fixed the problem and I now believe that Yahoo has unblocked this IP so there should be, I hope, no more problems.

Note that you may still see emails mistakenly labeled as spam so be sure to check your spam box and then label site emails as valid.  In Yahoo mail, select your spam folder, then tick all SB emails and then click not spam button in the top bar.  For gmail the process is similar, click folders expand arrow in left hand side menu to reveal spam folder.  Click spam folder to view spam emails.  Tick all SB emails and click "not spam" bottom at the top.  Note do this for all SB emails to train the filter to accept them as valid even if the emails are old and you plan to delete them (i.e. delete from inbox not spam box).