For several days, many of my sent emails have been not delivered and I have had various messages from mailer-daemon/ "This is the mail system at host know-smtprelay-6-imp." such as The remote mail system said; 553:information. (#5.7.1) and 550:5.7.1 spf policy (FAILED) Some emails are getting delivered but not many.
Any ideas what the problem is and how to solve it please?
(my email sending address is a tiscali.co.uk one, in case that makes any difference)
I know this is an old post but I came across it while doing a search and wanted to add some information that may be of use should anyone find it.
Looking at the original post the sender was sending through Virgin Media's smtp servers using their tiscali.co.uk address.
While this used to be possible without issues, TalkTalk - who own tiscali addresses have set up policies to prevent their email addresses being spoofed. I should add that there is no suggestion here that the OP in this post was anything other than a legitimate tiscali user.
All emails for tiscali sending addresses need to be sent through the following outbound server.
smtp.tiscali.co.uk Port 587 SSL Yes - TLS if using Outlook or Windows Live Mail StartTLS in Thunderbird. Username and password are the same as for inbound mail.
These changes affect other domains which are also looked after by TalkTalk - More information on the correct settings are here