[Hampshire] Posting to newsgroups - ISP blocking?

I have several times in the last few days tried to post to linux.debian.user
using Icedove (Thunderbird) and the post has never appeared. I have tried 3
accounts, my ISP's own news service (Newnet), and 2 third party news
services free.teranews.com and eu.Usenet-News.net, all without success. I
have just now suceeded by sending from a googlemail email account.

Also I currently have problems with my ISP's newsgroup service (
news.newnet.co.uk) as it seems to miss most of the postings to
linux.debian.user. I have submitted a ticket to ask them to look into this
but have got no reply. Otherwise their broadband service is very good but
their news service seems to be very unreliable and I suspect they have
blocked or just dropped my attempted postings. Is this a common problem with
UK ISP's?

Russell