MX Record priority and LOCAL mail handler

#1
Hi,

I am hosting my own mail server at home and my ISP blocks port 25. I have to use port forwarding (classic 25 -> 2525). I am forced to use PREF = 5 for my server's priority.
I am trying to overcome the case where my server goes offline (say power outage for example) and would like to implement mail mapping (@LOCAL) as a fallback solution. So I need to have my server's DNS tried first (on port 2525) and if it fails get ZoneEdit to parse and forward each email to some specified address.
From my testing, it appears that ever since I specified my new mail map, it looks like it took over all email management and it just parses and forwards each email address to the specified address (I keep track of email statistics on my server and they all fell to 0 since the mail mapping)
With all this, what I am suspecting is that LOCAL (which is supposed to be the back up and cannot be specified explicitly in the MX section, it is implicit), has implicitly a lower PREF (likely 0) than my server's DNS PREF (forced to 5 because I am forwarding to port 2525), so any incoming exchange is just parsed and forwarded instead of attempting to "blindly" deliver as-is to my mail server.
Anyone's got an idea on how I could get my server (with the 2525 forward) to take precedence over ZoneEdit's LOCAL email handler?

Happy holidays folks!
 

El.

Administrator
Staff member
#2
Hello and Happy Holidays! As you have suspected, backup MX via ZoneEdit is automatic, and does not need to be specified via LOCAL in MX. As well, mailmaps cannot be used as a backup to your primary mail server when port forwarding is specified in the MX record. Again, as you have deduced, email is handled as mailmaps for the domain name.
 
#3
Hello and Happy Holidays! As you have suspected, backup MX via ZoneEdit is automatic, and does not need to be specified via LOCAL in MX. As well, mailmaps cannot be used as a backup to your primary mail server when port forwarding is specified in the MX record. Again, as you have deduced, email is handled as mailmaps for the domain name.
Thanks for the (honest) response!
Just one last little question: If there was no port forwarding (my ISP had port 25 open), would my whole plan work? would I be able for instance to set the PREF for my server's dns to 0 and have it be the first handler for my emails, and then LOCAL would come in, if my server fails? I guess the real question is: what would LOCAL's PREF value be in this case?
Thank you!
 

El.

Administrator
Staff member
#4
Hello again. For the time being, it MAY work as you intend if port forwarding is not set up, but there is the possibility of error. Also, changes are coming to the ZoneEdit mail server structure which will only allow backup MX to be used as queued email and not for mailmaps.
 
#5
Hello again. For the time being, it MAY work as you intend if port forwarding is not set up, but there is the possibility of error. Also, changes are coming to the ZoneEdit mail server structure which will only allow backup MX to be used as queued email and not for mailmaps.
Thank you El. This should still work with me, because I still can set my registrar's MX servers as backup and have him exclusively do the mailmapping after my home server fails.
BTW, I was digging into this priority thing and stumbled into SRV records and I am sorry but a question popped up: If I create an SRV record for smtp protocol pointing to my Dyn DNS for my server and port 2525, can I use it in the MX section with PREF 0?
If yes would you mind sharing an example of how to create such a record? (just to avoid another post :))
 

sproskin

Administrator
Staff member
#6
Hello.

Can you please clarify the purpose of an SRV record for your server?

SRV records are separate from MX records. The priority of your MX records should can be handled by the MX records alone and do not require an SRV to operate.
 
#7
Hello.

Can you please clarify the purpose of an SRV record for your server?

SRV records are separate from MX records. The priority of your MX records should can be handled by the MX records alone and do not require an SRV to operate.
Hi,

The problem with the MX Record (at least with ZoneEdit), is when you use port forwarding (something like mydomain.dds.com:2525), the handler forces the REF priority to the single value 5. So any backup I use would have to have PREF 6 or higher. Finally LOCAL (implicit fallback) has a lower PREF (likely 0).
My idea (and question) was to try to create an SRV record for mailserver.dds.com that would implicitly point to mydomain.dds.com:2525 which I could then use to set my MX Record and assign it a PREF of 0.

Does this all make sense?
 
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