SQLite Forum

can not subscribe
I had a similar problem with a week-and-a-bit ago: a regular group email that I send, and had been working for several years, bounced for Outlook-related addresses (@live.co.uk and @hotmail.com), with Outlook saying:

550 5.7.1 Unfortunately, messages from [www.xxx.yyy.zzz] 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. [AM6EUR05FT014.eop-eur05.prod.protection.outlook.com]

I had to get my ISP to "de-list [the IP of their mail server] from [Outlook's] blocklist", so I strongly suspect Richard, as the owner/maintainer of the IP-address sending SQLite's emails will have to do the same.