A note to e-mail correspondents: I discovered late Friday that for about a week some e-mail messages I sent out were never received, even though I received no error messages. I have no way of knowing whether incoming messages were similarly blocked. And right now my e-mail is completely down.
If you have e-mailed me in the past week or so and have not received a response, it may not be the usual problem (too much e-mail), but instead it may be that I've not received your message, or that I sent a reply, but it was blocked.
The way to get around whatever is blocking my e-mail seems to be to strip all links (for example from signatures) out of an e-mail. Attachments may also be a problem.
Apologies for this inconvenience.