Add the ability to download/upload a list of the domains from Whitelist of Blacklist (Tools&Settings > Mail tab) as a text file so it is possible to add all the required domains at once.
The following Uservoices matching this feature were already created serveral times:
https://plesk.uservoice.com/forums/184549-feature-suggestions/suggestions/15998113-server-wide-e-mail-settings-blacklist
https://plesk.uservoice.com/forums/184549-feature-suggestions/suggestions/17805055-download-and-upload-for-the-email-blacklist-in-ord
https://plesk.uservoice.com/forums/184549-feature-suggestions/suggestions/6345455-mail-server-settings-bulk-emails

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

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.

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

If you have configured additional delimiters in postfix (/etc/postfix/main.cf) it is not possible to successfully deliver a mail to a mailing list - if that mailing list address contains also one of the symbols configured as delimiter.

The solution is very simple and could be a very generic change in plesk standard config:

In /etc/postfix/master.cf just change the config string for mailman in the end of line from ${nexthop} ${user} ${recipient}
to:
${nexthop} ${mailbox}
This will parse all necessary parameters before the @.

Taken from: http://www.postfix.org/pipe.8.html

Additional Administrator Accounts would like to stop receiving certain emails generated by Plesk. Would like to be able to control these.

Recent example of one not needed by one additional admin
"Could not issue/renew Let`s Encrypt certificates for Administrator"

Add to email address mailbox configuration - after mailbox size.

I would like to see the possibility to enable periods ('.') in email folders. Reason for that is that there are some webshops around here using the period as full store name and I would like to keep those emails in a separate folder.

As Google or Microsoft mail service, it can be great if when a user of a mailbox the name of the sender is overwritten by plesk.

Like this, we can provide a better and secur mail server. Mainly for developper or webmail.

Exemple :
I use the mailbox JD@domain.com and on few mailserver (as google), the sender will be JD if we use webmail, php script, etc. But if when we create the mailbox, and we assign the name "John Doe" to this mailbox, the sender will be John Doe.

Thanks for your help

Hello,

It would be amazing to be possible to create a distribution list via Plesk Premium email without creating a mailbox and forward the emails.

eg. create a example@example.com without a mailbox and forward to a group RH or Sales.

Hi!
It would be great if the autoresponder may switch on for a whole domain

For our customers I need to be able to use "smith.domain.com" as their Email Username, as opposed to their email address

extend the webmail settings screen like the php settings.
show the amount and which domain is using which webmail client and allow changes to it.
now after the horde desaster it would be way easier to identify domains using it and changing that.