![]() If a SMTP client tries to use a command which hMailServer has no implementation for, this error message is sent to the client. hMailServer does not include support for the TURN verb. If a SMTP client tries to use the TURN command hMailServer responds with this error code. This error message is issued if the domain address given in the HELO command does not have the correct syntax. This error message is issued if the domain address given in the EHLO command does not have the correct syntax. This error typically indicates a client defect or a hacking attempt. If a SMTP client sends a SMTP command which hMailServer considers beeing too long, hMailServer issues this error. This error message is issued if grey listing is enabled, and the sender, recipient and IP address triplet does not match an existing greylisting triplet. A client should never do this, but incorrectly configured clients could cause this problem. This error is generated by hMailServer if a client sends a large chunk of data to hMailServer not containing a newline character (command terminator). 421 Excessive amounts of data sent to server. The SMTP timeout in hMailServer is 10 minutes. If there is a timeout while hMailServer is waiting for a command from the SMTP client, this error message is sent to the client before hMailServer disconnects the client. ![]() If this is for all new mail to a particular fussy domain owner (irrespective of where the mail is from), then a stand alone instance of hMailserver will achieve what you needĪnd then you could always use postfix if that does what you want.SMTP error messages 421 Connection timeout If this is ONLY for communication between you and the client, then a custom config at both ends will work, as would a VPN **Unless you and your client are actually testing for a specific certificate, man-in-the-middle can still happen **Spam comes via encrypted connections very often (ever get spam from a gmail or account - that will have arrived via an encrypted connection) I'm really struggling to see the use case. They put their own certificate in the middle to decrypt, then re-encrypt mail connections. Most client level antivirus that inspect SSL mail do exactly a man-in-the-middle attack. Man in the middle can happen because the certificates aren't validated Which looks to me like the postfix documentation you linked STARTTLS is susceptible to Man-in-the-Middle attacks, as the exchange about the availability of encryption is not encrypted. In the Ports section of the GUI, just set all standards ports to 'require TLS' Which just made me think that solution does not enforce encryption for outgoing mail, only for incoming mail: This customer will need a dedicated hMailserver** Set a port to 'require StartTLS' or to 'SSL', and ONLY encrypted incoming connections matching that encryption level will be usedįor outgoing setting a route to the appropriate encryption level will work If there was an IP range option "Require SSL/TLS for all connections", this would be a viable solution They don't AUTHenticate, but they do encrypt the connection Many messages are sent to my server via an encrypted connection from people / servers that I don't know (including much SPAM). You do understand that encryption is NOT the same as AUTHentication. "External to local e-mail-addresses") cannot require authentication, since external mail servers don't have credentials. If you don't have a dedicated hmailserver** for this customer, how will you know which connections to encrypt and which ones to allow unencryptedĪn IP range with "Require SSL/TLS for authentication" would not cover our case, because connections between mail servers (i.e. Like this we could create a dedicated "TLS only" email address. To avoid missing mail by other customers, we would prefer to "require TLS" on the mailbox level. Basically, all mails of all communication partners are encrypted via a Forced TLS connection.ĭoes hMailServer support this? And if not, how much would it cost to sponsor this feature? If a connection fails due to an error situation, the mail transport is rejected and the sender of the e-mail receives a Non Delivery Report (NDR). ![]() Forced TLS connection emails will encrypted mails in all cases between transmission of communication partners. The encryption takes place between the Internet access points of the two communicating companies and is automatically carried out without any actions by the communicating communication partners (users). ![]() hMailServer should only accept email from/send email to another mail server if the connection is encrypted, and trigger a Non-Delivery Report otherwise:Įncrypting mail transmission via Forced TLS (Transport Layer Security) Transport Layer Security encrypts the transmission of e-mail over the internet. A new customer requires us to set up "Forced TLS", i.e.
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