Same problem here for last 2 weeks. Some days I cannot send only through webmail. It may last for a few days then back to normal.
I have been doing research on this.
I am using an ancient email client, Eudora 7.1. Last update was 2005. I found a thread yesterday from March 2023 that mentions that TalkTalk has changed it security protocols.
It was still allowing people with older clients, including win mail, to send, but if they continued to do so with out upgrading to a client prefered by TalkTalk, then they would start to block the customer from sending emails.
Apparently they did email people about this but I never received one. In extreme cases they may block receiving as well.
They were forcing people to use webmail untill they have upgraded their client. Apparently the moderator of the forum who was a talktalk emplyee, said that after you upgrade your client you would have to contact customer support to tell them what you are using and your settings in order to be unblocked from sending emails through your new client.
I am now in the process of migrating to Thunderbird, but have found that this also has problems. Yesterday it was ok to send , but now it isn't. So there seems to be a problem woth TalkTalk servers and not after all that they were just blokcing me because I am using Eudora.
