22-05-2021 02:01 AM - edited 25-05-2021 03:25 PM
Noted that as of 21 May 2021 the tiscali SMTP outgoing mail server was not passing on mail messages to the TalkTalk Mail platform although tiscali outgoing mail is flowing normally to other mail services.
The talktalk.net SMTP outgoing mail server is working normally.
The fix for users of the tiscali.co.uk domain, legacy tiscali family domains and pipex domains is to use the TalkTalk recommended Email settings - IMAP & POP3 and as given in the top of forum topic Upgrade your legacy mail settings.
on 25-05-2021 03:25 PM
This fault appears to be fixed.
Noted that as of 3pm on 25th mail sent by smtp.tiscali.co.uk is being promptly delivered to the TalkTalk Mail platform sent by smtp-out-11.tiscali.co.uk to the TalkTalk Mail platform at Open Xchange.
3 buffered messages have just been delivered (14:43 to 14:49) after 4 hour, 14 hour and 21 hour delays. The only discernible difference is that the mail messages were sent by smtp-out-12.talktalk.net to the TalkTalk Mail platform at Open Xchange.
on 23-05-2021 01:27 PM
A mail message sent on Saturday using the smtp.tiscali.co.uk outgoing server host has just been received after a 9 hour delay  before being passed on to  where the TalkTalk Mail mailboxes are hosted.
 at smtp-out-2.tiscali.co.uk 126.96.36.199 to mx.talktalk.net
 smtp-out-9.tiscali.co.uk 188.8.131.52 for the mx.tt.xion.oxcs.net servers
This, to me, indicates the mail sent by the smtp.tiscali.co.uk outgoing server host that is incoming for the TalkTalk Mail platform is being deferred or dropped without warning. So this points to the CloudMark spam protection and mail filtering system.
Mail messages sent by TalkTalk Mail legacy domain users (using smtp.tiscali.co.uk) to other TalkTalk Mail users are being dropped or delayed and no bounceback message issued to those originators of such mail messages. See post 1 for the user fix to send via smtp.talktalk.net outgoing server host name.
NB The same mail message was received without delay by Yahoo Mail and messages originated and sent using smtp.talktalk.net are passed without delay.
There's no indication of a blacklist issue involving any of the servers and SPF and DKIM checks pass OK.
Needs a prompt fix and notifications for deferred and dropped mail messages inbound to TalkTalk Mail users. TalkTalk have been notified via the prescribed PM process.