Ports 995 & 993 work for some users and others no

[foxmedo]

Hello,

we are facing to a problem for which we didn't find a solution we have some users who are able to connect over 995 and 993 but others are not able to connect

they are in the same company and if we change the ports to by default 110 & 143 it will work without any problem

FYI it's new server on which we just move and we have copy all our config from the old sever

On this new server we are using CloudLinux it can be a ressource limitation problem ?

any suggestion ?

Best regards

 

[cPanelLauren]

What is the error when they do connect over 993 or 995 and it fails? Please see Forums Guidelines and FAQ for the kinds of information that is helpful.

 

[foxmedo]

Hello @cPanelLauren,

Thank you for your feedback,

The error users getting is

Your server does not support the connection encryption type you have specified. Try changing the encryption method. Contact your mail server administrator or Internet service provider (ISP) for additional assistance

and most of them are using outlook 2013 with windows 7, others are using outlook 2010 with windows 7

 

[cPanelLauren]

Are they using SSL or TLS/STARTTLS as the encryption type? Keep in mind that SSL should not be used, TLS or STARTTLS is the correct encryption type.

 

[foxmedo]

i have solve the problem by changing the cipher from

ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384

to

ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS

i have copie the cipher from our old server

i don't know my client has more than 200 emails account who use outlook if they are using SSL or TLS no idea about this but i think for the POP3 there is no way to choose you have a checkbox with this account use secure SSL

 

[sparek-3]

Some of your clients are probably using old email clients or old operating systems that don't support up-to-date TLS (which currently means just TLSv1.2) or secure ciphers.

Such is the nature of the beast. you either have to placate your clients and make your server less secure or force your clients to update to newer operating systems and email clients.

 

[foxmedo]

@sparek-3 yes my clients has win 7 and outlook 2010, win 7 with outlook 2013 and others has windows 8.1 with outlook 2013

for users who has win 10 and new outlook version it's work without any problem

we have choose to less secure as the server is used only for mail and host some websites and our clients need more time to buy new computers, it's another budget

by the way i need to know from an experienced person like you what is optimization we can do to optimize our server to be compatible with Outlook client and to use less bandwith.

we have asked many time our clients to use webmail but as you know roundcube & horde are horrible and and they lack options, users doesn't accept to use them

Any suggestion from your side ?

 

[sparek-3]

Probably needs to be it's own topic here. But I'm not really aware of any level of bandwidth optimization that can be put in place for email.

I mean... if they are checking their email using IMAP, I suppose that could potentially use more bandwidth than checking it via POP3. If you have an email message with a ton of images and attachments - say that message is 500KB. With IMAP if it's viewed once, that's 500KB. If it's viewed a second time, that's another 500KB for a total of 1000KB. A third... a fourth... a fifth... that COULD potentially start to add up after some time. With POP3, the message is downloaded once to the user's email client. So 500KB. View it a second time... it's loaded from the user's local computer so 0KB is transferred. A third time... 0KB.

BUT... POP3 really can't be used if you're checking a mail account across multiple devices. If a user is checking an email account on their computer and their phone. Then once either client downloads the mail as POP3, the other one won't be able to see it. Not to mention that phones typically don't have the storage capacity to handle downloaded mail. That's why pretty much all phone mail apps are going to default to IMAP.

But if you're seeing 100's of GB of bandwidth being used by IMAP... I'd say something is wrong. It's going to take A LOT of views of 500KB messages to reach 100GB of bandwidth.

 

[cPanelLauren]

There really isn't optimization that can be done for bandwidth usage. There are some things you can do to limit it:

- You can limit a cPanel users bandwidth usage - Limit Bandwidth Usage | cPanel & WHM Documentation so they can't overconsume
- You can limit the attachment size for messages using exim configuration manager -> advanced editor -> message_size_limit
-You can only allow POP3 - this doesn't synchronize mail between devices, just downloads to the current device retrieving the mail.

 

[Handssler Lopez]

In addition to what colleagues say, I recommend using Mozilla Thunderbird, it can be installed on computers with an old version of windows and can work with current ciphers, it is a good alternative option to outdated Outlook and you can import emails from outlook to thunderbird.

I hope my comment is helpful