It would be much better if server-wide and per-mailbox options were available in Plesk to add SpamAssassin rules.

SpamAssassin can be configured by the command line, but this is difficult for many of us.

There is an spam filtering option to "Move to spam folder XXXX" on Linux, but not on Windows (Plesk 11+).

Unfortunately, horde doesn't work so well and every time when a message with broken header arrives, horde displays "Invalid Address" and no subject to all inbox messages. The described fix in https://kb.plesk.com/en/121175 doesn't work in this cases, forcing us to find the broken message manually (or scripting something to do the dirty job).

This feature should exists in Windows env as in Linux.

The implementation of the centralized smartermail in plesk onyx for windows is good, but it should also be possible to integrate this feature into the linux edition.

Many hosters provide both windows and linux hosting with ONE centralised mail solution. Since the integration for winodws is already done I suppose it shouldn't be too hard to integrate it into the linux version as well since smartermail is completely API based.

This would allow you to see mailboxes that are no longer in use.

The DMARC support in Plesk Onyx 17.5.3 ist incomplete. If an incoming email is rejected due to a DMARC fail there is no mailer daemon generated to inform the sender of this email.

Please add this important feature to DMARC support. Otherwise it would not be usable for most customers.

Sometimes is useful check the details about POP3/IMAP/SMTP traffic for a single email, to look and find problems.

I would be a good Idea to be able to change webmail URL via Plesk, not using workaround https://support.plesk.com/hc/en-us/articles/213947325-How-to-set-up-an-access-to-webmail-over-mail-example-com

All incoming/outgoing mail for a certain domain is copied automatically to a different inbox within that domain.

http://forum.sp.parallels.com/threads/email-archive.92570/

Add functionality to import csv files to create multiple e-mail accounts from a list in Plesk Panel

It seems difficult to manually install a mobile skin on Roundcube, and if it should succeed the plesk would overwrite the config made on updates. The default skin provided with plesk should support mobile devices, as this is an important feature nowadays.

With option to disable or enable.

Can be installed manually but all guide are now old and nothing for Onyx.

This worked really well for me on 12.5.

Allow users and admin to select subject lines and keywords as well as keywords in the email body to be added to the spamfilter blacklist.

Currently spammers are just changing domains and sending the same email templates.

I would like to enable and configure fetchmail on mailbox level. Main reason is easy migration for customers to new hosting providers including moving mails from existing mail servers.

"fetchmail" is already installed together with PLESK, needs just to get properly configured.

Make SPAM and Virus statistics visible on linux like on windows

Into domains blaklist frequentelly we have subdomains sendind emails,
so block just a domain not solve the situation.

i suggest a check option to block all subdomains as well,

please see the post forum for more info.
http://forum.odin.com/threads/is-black-list-server-wide-mail-settings-working.333066/#post-780648

Ability to change settings in the mail autodiscover - for example, to set the mail server that will be set in the mail client.