During this week I have been informed of several emails to me being returned as undeliverable. I have now discovered that my 'quota' had been exceeded. However, apparently all it needed was for me to tick the box marked 'unlimited' for the problem to be resolved!
So, if you have written to me at email@example.com recently and had problems getting through, I do apologize and ask you to try again, as hopefully it is all sorted out now.
(Needless to say my daily Japanese spam email comment on this blog got through - still at least with the advice of my friends here, it now comes to me for moderation (ie delete) before it appears here!)