If you ever need to specify a blank sender in the mail from command when debugging an SMTP server by using a Telnet client; use <>. For example: 220 mta.domain.com Microsoft ESMTP MAIL Service ready at Mon, 22 Dec 2008 23:21:41 +0100 ehlo 250-mta.domain.com Hello [10.10.10.10] 250-SIZE 250-PIPELINING 250-DSN 250-ENHANCEDSTATUSCODES 250-STARTTLS 250-X-ANONYMOUSTLS 250-AUTH NTLM 250-X-EXPS …
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