There's only 5 mailboxes (ie a...@mydomain.com, b...@mydomain.com, ..., e...@mydomain.com) that I'm hosting & it's using postfix. The above 5 mailboxes only receives emails from 6 external domain ie these 5 mailboxes don't send emails out.
Does the above describe it? >It is also surprising that you are trying to discover this unilaterally, >rather in coordination with the administrators of these domains. Someone suggested to me to use www.mxtoolbox.com, key in the domains (there's about 6 of them only) & the above site will provide me all the email/SMTP servers of those domains. Isn't this sufficient or there's flaws with this? I still need to clarify the following doubt: > So is it right to say that though I want only a small handful of > users from certain domains/organizations to send email to me, > it could be email gateways (or "mail relay servers" ??) that are > unrelated to those domains/organizations that make Tcp25 > connection to my email server? Thanks On Fri, Jan 28, 2011 at 11:51 PM, Victor Duchovni < victor.ducho...@morganstanley.com> wrote: > On Fri, Jan 28, 2011 at 11:36:28PM +0800, sunhux G wrote: > > > So is it right to say that though I want only a small handful of > > users from certain domains/organizations to send email to me, > > it could be email gateways (or "mail relay servers" ??) that are > > unrelated to those domains/organizations that make Tcp25 > > connection to my email server? > > You have not described in any way what kind of recipient mailboxes > you hosting, and part of the story is lies in recipient behaviour. > > If recipients forward mail received at other mail domains to your domain > for delivery, then you need to consider supporting mail clients that > are handle mail forwarding for those domains or to "encourage" your > recipients to not forward. > > You also need to understand whether any of the legitimate sending users > send email via unexpected origin systems: > > - Outsourced vendor mailings > - Consumer cloud services that send email (Evite, Newspaper > forward to a friend services, ...) > - ... > > It is also surprising that you are trying to discover this unilaterally, > rather in coordination with the administrators of these domains. > > > As for the external POP3 clients that connects to my POP3 > > server (which runs in the same box as postfix), it makes sense > > to permit on my firewall for those POP3 clients to connect? > > POP3 and IMAP are for recipients, not senders, you've not described > the recipient requirements at all. > > -- > Viktor. >
