Some newsletter mails aren't delivered

[amkay]

Hi!

I configured my mailbox to reject mails that are delivered via unencrypted SMTP connections and I think also TLS encrypted SMTP connections with weak ciphers.
Since then only some newsletter mails were delivered to my inbox, all others were rejected.

I think the root of the problem is that some servers at createsend are misconfigured.

From what I can tell by now, these servers use TLS encrypted connections with strong ciphers:

• mx65.b.outbound.createsend.com
• mx200.a.outbound.createsend.com
• mx201.a.outbound.createsend.com
• mx202.a.outbound.createsend.com

These servers either use no transport encryption or TLS encryption with weak ciphers:

• mx147.g.outbound.createsend.com
• mx35.b.outbound.createsend.com

It would be really nice if this could be fixed.

Thanks and kind regards.

[jerodsanto]

Appreciate you raising the issue!

We're not in control of these servers, Campaign Monitor is. That being said, I've been considering a switch off CM for our email delivery for some time and this is one more nudge in that direction. Two questions for you:

1. Do you know if Postmark's SMTP servers suffer from this or similar misconfigurations?
2. Do you have a tool/command that I can use to test for this repeatedly?