The SHA1 algorithm will soon be considered deprecated. So, if you have an SSL certificate using this algorithm, it's time to replace it. No hurry needed, but before the end of the year will be wise. Ask your SSL certificate supplier if they offer a free renewal, because many do.
The SSL certificate used by this website was also signed via SHA1. But thanks to Chris Wadge, who donated the certificate, the Hiawatha website is now back to an A+ score.
Google tried to deliver your message, but it was rejected by the server for the recipient domain leisink.net by leisink.net. [141.138.201.249].
The error that the other server returned was:
454 4.7.0 TLS not available due to local problem