Apple Mail Since upgrade to dovecot 2.3.x unable to connect

[Aki Tuomi]

> On 17/08/2020 12:51 Johannes Rohr <jorohr at gmail.com> wrote:
> 
>  
> |Dear all,|
> 
> |a couple of days ago I upgraded our server from Ubuntu 18.04 to 20.04,
> thereby upgrading dovecot from 2.2.x to 2.3.x.
> |
> 
> |Since then, some older versions of apple's mail.app (bundled with el
> Capitano, released in 2016) no longer connect. When I turn on SSL
> debugging, I see:|
> 
> |Debug: SSL error: SSL_accept() failed: error:14209102:SSL
> routines:tls_early_post_process_client_hello:unsupported protocol
> imap-login: Debug: SSL error: SSL_accept() syscall failed: Invalid argument|
> 
> ||
> 
> |Unfortunately, it doesn't reveal the name of the unsupported protocol.
> Also, what about the failed syscall? Does dovecot try and fail to open
> some file?|
> 
> |Here are the contents of /etc/dovecot/conf.d/10-ssl.conf:|
> 
> |    ssl = yes
>     ssl_cert = </etc/ssl/letsencrypt/idaweb-mail.rooot.de/fullchain.pem
>     ssl_key = </etc/ssl/letsencrypt/idaweb-mail.rooot.de/key.pem
>     ssl_ca = </etc/ssl/letsencrypt/idaweb-mail.rooot.de/ca.pem
>     ssl_client_ca_dir = /etc/ssl/certs
>     ssl_dh = </etc/dovecot/dh.pem
> |
> 
> |I would greatly appreciate any hints!
> |
> 
> |Cheers,|
> 
> |Johannes
> |
> 
> |
> |
> 
> ||

You need to set

ssl_min_protocol = TLSv1.2 # or TLSv1

Aki