I receive incoming emails but cannot send out. They stay in the 'Out' box. In Mail Preferences it says 'Outgoing Mail Server (SMTP) - in the slot is 'concordmedia.org.uk I am using IMAP system.

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    I have a feeling it's because your ISP may have switched off TLS1.0 support. El Cap Mail cannot do TLS1.2, so you'll have to try find a mail client that does. I'd check with your ISP to be certain.
    – Tetsujin
    Oct 1 '20 at 15:11
  • Thanks Tetsujin, I will investigate that. Eric Oct 1 '20 at 16:54
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    – bmike
    Oct 1 '20 at 18:06
  • @Tetsujin This is not true! Apple Mail (and Apple Transport Security in general) added TLS 1.2 in 10.9 Mavericks in 2013. Oct 2 '20 at 1:37
  • Google spits a whole slew of issues with El Cap & 1.2
    – Tetsujin
    Oct 2 '20 at 9:13

Not a lot to go on, but here are the steps I follow:

Is there a guide from your organization that explains how to configure Apple Mail or even a configuration profile so you can enter the settings perfectly without having to enter them manually?


It is very unusual for an email server's SMTP address to use the same address as its parent website. It is much more usual to use an address starting with smtp.

A DNS lookup for smtp.concordmedia.org.uk gives different result to concordmedia.org.uk, so I am confident that your issue is an incorrectly specified SMTP server. Try smtp.concordmedia.org.uk.


If the problem is due to El Capitan having insufficient HTTPS support (likely outdated cipher suites), you can fix the problem by setting up a local proxy server and routing https traffic through that. https://forums.macrumors.com/threads/fixing-https-issues-on-old-versions-of-os-x.2281326/

This would be the first instance I'm aware of in which a server dropped support for all of El Capitan's cipher suites, but it's plausible, as it has happened on older versions of OS X.

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