How to find the source of exceeded Outgoing Mail Control limits via Plesk interface?
Plesk does not have such functionality at the moment.
Vote for this feature at Plesk UserVoice here or here. Features with most requests are likely to be implemented in Plesk in the future.
As a workaround:
1. Locate the domain with exceeded limits, open Tools & Settings > Outgoing Mail Control > Domains
2. (Linux) Locate mail addresses exceeded the limits, open Tools & Settings > Outgoing Mail Control > Email Addresses.
3. Locate the mail sending attempts for the located email account, look into SMTP service log file:
- For Windows, it is in MailEnable console: Servers > SMTP > Logging > Activity
- For Linux, it is: