Go to your mailbox via the TalkTalk Mail webmail sign in and then create a new email message to send to yourself i.e. the same mailbox address and tell us if that gives a send error message and if so what that message is:
Select here: Sign in to TalkTalk Mail
Enter your TalkTalk email address and password, select Sign in.
Select the New email button, or pencil icon if using a mobile browser, to compose and self-send the same mailbox a mail message. Check that the message sends without error, is copied into the Sent folder and arrives in and stays in the Inbox.
Let us know of any error message, or if mail did not arrive in the Inbox or disappeared from the Inbox.
If sending works via the online mailbox then tell us what email app or email software you were using that doesn't allow you to send mail messages. If, for example, the outgoing server settings are using port 25 for outgoing mail then because that is for sending unencrypted mail it is deemed insecure and has not been permitted for the last two years. Some older Operating systems or email software do not support encryption to the TLS 1.2 standard but almost all up to date email software does support the required email settings for TalkTalk Mail.
