roehling
commented
4 years ago The slash is part of the base64 encoding of the signature that prevents the spoofing of rewritten addresses. According to RFC 5322, a slash is a valid local-part character and should be accepted as sender address, so the behavior exhibited above is a protocol violation that should be reported to the server admin.
Theoretically, I could replace the slash by a different character in the base64 alphabet, but I seriously doubt that any of the remaining valid characters is more likely to be accepted than slashes (curly braces, anyone?)
Therefore, I'm closing this issue.
Hi,
Some MTA servers responds SMTP Invalid sender address (in reply to MAIL FROM command), if the SMTP mail from contains '/' slash character. Is it possible not to use slash character in SRS.
I use postsrsd 1.4 on Debian 9.
Example:
> telnet 62.112.192.40 25
Trying 62.112.192.40... Connected to 62.112.192.40. Escape character is '^]'. 220 avgw.enternet.hu ESMTP Exim 4 Fri, 03 Apr 2020 14:38:51 +0200 ehlo mail.opennet.hu 250-avgw.enternet.hu Hello mail.opennet.hu [91.223.222.53] 250-SIZE 52428800 250-8BITMIME 250-PIPELINING 250 HELP mail from: SRS0=mLwe=5P=test@opennet.hu 250 OK
> telnet 62.112.192.40 25
Trying 62.112.192.40... Connected to 62.112.192.40. Escape character is '^]'. 220 avgw.enternet.hu ESMTP Exim 4 Fri, 03 Apr 2020 14:40:15 +0200 ehlo mail.opennet.hu
250-avgw.enternet.hu Hello mail.opennet.hu [91.223.222.53] 250-SIZE 52428800 250-8BITMIME 250-PIPELINING 250 HELP mail from:SRS0=mL/e=5P=test@opennet.hu 550 Invalid sender address 421 avgw.enternet.hu: SMTP command timeout - closing connection Connection closed by foreign host.
Best Regards.