SMTP 550 Error

[webstergm]

Hi, I am the secretary of a Community Council in Scotland and we have a website hosted for us which also provides Roundcube as an email service. I personally use Outlook and have all the Roundcube email forwarded to a separate secretarial account in Outlook. I've been using Roundcube Webmail for about two years now without any issues up until now. On Wednesday I sent out an email to an established distribution list and had four emails bounce back with a 550 error. Looking at the four failures there are two @hotmail.com, one @hotmail.co.uk and one @msn.com. All the other recipients not on hotmail or msn received the email ok. As an experiment I sent the message again to the four failed recipients from my personal Outlook account and these did not fail. This appears then to me to be either a Roundcube issue or with the hosting provider. I need to get this sorted asap, can anyone advise please?

This is the error message:

Mail Delivery System [email protected]

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:

[email protected]
host hotmail-com.olc.protection.outlook.com [104.47.56.33]
SMTP error from remote mail server after pipelined MAIL FROM:<secretary@communitycouncilwebsite> SIZE=801672:
550 5.7.1 Unfortunately, messages from [193.189.75.224] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [DM3NAM02FT024.eop-nam02.prod.protection.outlook.com]

[email protected]
host hotmail-com.olc.protection.outlook.com [104.47.56.33]
SMTP error from remote mail server after pipelined MAIL FROM:< secretary@communitycouncilwebsite > SIZE=801672:
550 5.7.1 Unfortunately, messages from [193.189.75.224] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [DM3NAM02FT024.eop-nam02.prod.protection.outlook.com]

[email protected]
host msn-com.olc.protection.outlook.com [104.47.59.161]
SMTP error from remote mail server after pipelined MAIL FROM:< secretary@communitycouncilwebsite > SIZE=801672:
550 5.7.1 Unfortunately, messages from [193.189.75.224] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [DM6NAM12FT043.eop-nam12.prod.protection.outlook.com]

[email protected]
host eur.olc.protection.outlook.com [104.47.18.225]
SMTP error from remote mail server after pipelined MAIL FROM:< secretary@communitycouncilwebsite > SIZE=801672:
550 5.7.1 Unfortunately, messages from [193.189.75.224] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [VI1EUR06FT013.eop-eur06.prod.protection.outlook.com]

[SKaero]

The errors aren't related to Roundcube, your hosting provider appears to have been added to Outlook/Microsoft's block list.

[webstergm]

Ok, thank you I will contact them.