still cannot send e mails has been like this foe over 8 days

I have not been able to send e mails for at least 8 days now last contacted TalkTalk 3 days ago and was told it would be fixed in 24-48 hours still no luck has any body else had this message and what does it mean in plain english?       UNKNOWN ERROR  SERVER S M P T TISCALI.CO.UK PROTOCOLS M P T SEVER RESPONSE 554 CM11 GB1 S M P T TALTALK NET E S M P T SERVER NOT AVAILABLE PORT 25 SECURE (SSL) NO.SERVER ERROR 554 ERROR NO 0x800CCC6F