OK. I've read previous posts in the matter of SMTP authentication and why sometimes it might fail (incorrect username, password, spam detection etc) but I am now reporting that in spite of repeatedly changing my Virgin password as instructed, the Virgin SMTP system quickly then reverts to failing again hence requires me to change my password yet again before I can get back on to send out emails. I have thoroughly checked all devices for malware and all such virus detection is reportedly clean. I have been using the Virgin SMTP service happily since 2007 with no problems up until this week in September 2021 when now this repeated SMTP failure has kicked in. So, there's nothing wrong with my credentials, so why does the SMTP failure keep on coming back?