When sending email from Plesk email address via Outlook Express to an external email address containing two or more consecutive dots in the local part (like "my..email@example.com"), email cannot be sent and the following error is recorded in the maillog:
Oct 18 13:18:17 myserver postfix/cleanup: 466082AA804F: milter-reject: END-OF-MESSAGE from unknown[18.104.22.168]: 5.7.1 Command rejected; from=<firstname.lastname@example.org> to=<my..email@example.com> proto=ESMTP helo=<KOJIPCI7>
CauseEmail addresses with where dots in the local part appear two or more times consecutively are invalid.
In principle email addresses with double dots are invalid and should not be used, however some mobile companies are still allowing such addresses. One of the following can be an effective workaround allowing emal from Plesk to be sent to such invalid addressess:
- Switch Plesk MTA to Qmail (http://kb.sp.parallels.com/5801).
- Avoid using Outlook Express. For example, Thunderbird is able to send email to such invalid email addresses.