It would be useful to be able to add domains to IgnoreMailFrom rule for DMARC check from Plesk interface.

Not sure how can this be implemented but mailboxes getting full from messages(spam) that gmail does not download

It would be nice if there is a way to auto clean undownloaded messages after a while

Currently, Plesk Premium Email can be enabled only for a subscription.
But Plesk Premium Email license differ by a number of users, so, to not exceed the license limit, it'll be handy to define which particular mailboxes on a subscription have the ability to use Plesk Premium Email

Add delete/reject option for addresses and or domains in the blacklist. If I've blacklisted a domain, chances are that I don't want anything from that source.

According to https://support.plesk.com/hc/en-us/articles/115000786914-How-to-enable-SpamAssassin-spam-check-for-forwarded-emails-on-Windows when the option "Apply individual settings to spam filtering" is enabled, filtering of forwarded emails is not performed and additional steps are required.

Please, make it so that no additional steps would be required.

Please add functionality to access webmail from Plesk interface without using a password.
The same functionality is enabled in cPanel. Please see section "Access webmail from the cPanel interface" of documentation:
https://documentation.cpanel.net/display/CKB/How+to+Log+in+to+Your+Server+or+Account#HowtoLogintoYourServerorAccount-AccessWebmaildirectly

Mail authentication brute force attacks generate additional traffic.
It is counted as a part of POP3/IMAP traffic statistics in Plesk for Windows.
Please add functionality to recognize and ignore such normal traffic so that it does not forge POP3/IMAP statistics.

Allow changing the percentage when the mail quota warning is sent, in small sized mailboxes the 95% could be almost to late.
So it would be good to have an option to adjust it for example to 85% or other values.

We would like to make the emails to be sent from our Ticketsystem mail and not from the Plesk admin mail

When installing Plesk with MailEnable, by default Plesk removes MailEnable logfiles every 24 hours.

According to this KB (https://support.plesk.com/hc/en-us/articles/115001102353), this functionality is made in purpose to optimize mail statistics, but this is not acceptable.

Additionally, you are offering the possibility to apply this workaround (https://support.plesk.com/hc/en-us/articles/213397889), but this workaround is not valid for us because we don't want to customize the FTP and HTTP logs location and we have the log files in different disk volumes.

Please, provide the possibility to configure the log rotation settings for MailEnable respecting our hosting company needs.

Plesk admin should have control over all possible mail notifications sent by Plesk. For example, Plesk admin should be able to enable/disable notifications which inform that Plesk failed to generate web server configuration files. Some Plesk owners may already have checks and notification mechanisms in place for Nginx/Apache, as well as several other services.

It would be a good idea to be able to set mail filtering for emails with specific Subjects in Plesk Email Security extension.

Currently all mailbox passwords(MailEnable) are stored in AUTH.TAB in plain text that is not secure.
MailEnable has an option to enable password encryption in AUTH.TAB

Add domain reputation based spam protection lookup such as the feed from dbl.dq.spamhaus.net, in addition to the existing IP DNSBL.

Currently, there are three buttons in the mail queue interface.
Refresh, Remove, Clear

These are fine when there is Spam in the mail queue but for normal emails, it would be nice to have an additional "Requeue" button.

Now, when I spot an email that shouldn´t be deferred I have to log in over SSH and execute: /usr/sbin/postsuper -r ALL to requeue them.

Just like the "Remove" button works for selected emails the "Requeue" button would work for requeueing selected emails.

The use case. Messages deffered to Yahoo when many messages sent:
421 4.7.0 [TSS04] Messages from IP temporarily deferred due to user complaints

Is it possible to add limit outgoing messages to specific service, for example:

Sent no more than 100 mail to Yahoo per hour

Allow the Pleask user to specify a mailbox with no (zero) capacity for the purpose of managing email from a 3rd party such as Gmail. This would allow email to be forwarded to Gmail without the exceeded capacity error but also allow Gmail to send mail through the mail domain. Currently this needs to be modified by admin and it's hard to explain each time to the admin.