Emails not sending in Outlook

Hello All,
Just switched to CloudFlare and suddenly emails in Outlook are not sending (on some networks only??!?) with the error “Your server does not support the connection encryption type you have specified”.
Incoming emails are fine.
How can I get Outlook to send emails?

EDIT - it actually only seems to work in my house! not at the office, not on my phone outside of the house…my home wifi is the only thing that can correctly connect to the outgoing mail server (but everything is set up the same way). Did I somehow do something where only my local IP can access the outgoing mail server?
Please help!

Kindly, see below how to resolve the issue.

May I ask which Microsoft Outlook version are you using?

Check headers of the mail, from where did it come from.

Does the error or info log file for the mail service have anything logged?

Nevertheless, re-check out your configuration if you are actually trying to sent out from your hostname (DNS record) which could be the main domain like and which is being proxied by Cloudflare (:orange: cloud), instead from the hostname which is being unproxied like :grey: cloud.

If the mail record is :orange:, then it’s 100% that the hostname does not resolve to IP address and vice versa as it sees Cloudflare as the “sending one”, which is not correct way (stated above, :grey: cloud should be).

There could be few issues, kindly see below instructions to re-check the needed DNS record for propper e-mail functionallity:

Cloudflare’s default configuration only allows proxying of HTTP traffic and will break mail traffic.

The DNS record(s) used for e-mail service (usually the A mail record) should be :grey: cloud at DNS tab on Cloudflare dashboard for your domain and the MX record should point to a hostname that is set to that unproxied (usually the A mail) with DNS only record.

Moreover, there are situations where people point their MX record to a CNAME or use some e-mail service like G Suite and other.

Some of the useful tools for testing e-mail functionallity:

Kindly, check to which port are you actually connecting, if so.

Furthermore, are you using an SSL certificate for your e-mails too?

Otherwise, it could be due to some ISP cache, or maybe you would need to add (if already not) autoconfig and autodiscover DNS records, just in case for Microsoft Outlook.

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