1

I need to setup coexistence between MDaemon (13.0.5) and a Microsoft Exchange system (Office 365); the two systems should share the same SMTP domain, and each one should forward to the other any message which has a recipient in that domain but is not local to the server; I already have safeguards in place against routing loops (using a custom header), so this is not an issue.

I have succesfully configured Exchange to route to MDaemon all messages which it can't deliver to its own mailboxes; this works without problems. Now I need to do the same on the MDaemon side.

I configured the relevant options in the "unknown mail" configuration section, but MDaemon keeps rejecting these messages with a 550 error (unknown user).

What am I missing here?

HopelessN00b
  • 53,385
  • 32
  • 133
  • 208
Massimo
  • 68,714
  • 56
  • 196
  • 319

2 Answers2

1

Answer found: you need to configure MDaemon to accept messages addressed to (or coming from) unknown local users, which are by default refused: http://help.altn.com/mdaemon/en/index.html?security__relay_settings.htm.

Account Verification

SMTP MAIL address must exist if it uses a local domain

Click this option is you wish to verify that the MAIL value passed during the SMTP process points to an actual valid account when it is purported to be from a local domain or gateway.

[...]

SMTP RCPT address must exist if it uses a local domain

Click this option is you wish to verify that the RCPT value passed during the SMTP process points to an actual valid account when it is purported to be from a local domain.

Massimo
  • 68,714
  • 56
  • 196
  • 319
0

Starting from the default configuration of MDaemon "POP before SMTP"

enter image description here

you will be unable to receive mails from Office 365 disabling Account Verification settings. The best way (more secure) is to add all EOP IPs to the Trusted IPs list on MDaemon and then flag the options to disable account verification for trusted IPs only:

enter image description here

EOP IPs are available at this link: https://technet.microsoft.com/en-us/library/dn163583.aspx

John
  • 21
  • 3