Add strict source plugin

[SH]

Add strict source plugin which don't allow sending emails with mailfrom (and From?) matching local domains via port 25 (unless its localhost or relay) and fail with message to client to use port 587/465 authenticated.

pros:

• it will force best practices, (and no tickets like #501, #497...)

cons:

• fits only case where there is only ONE smtp for domain (domain toggable?)
• deciding by From: header might broke groups messaging
• for old installation MUST be off by default

[Alexander]

Sounds perfect to me, thanks!

[SB]

Does this mean all clients will need to send using 587 going forward?

[Scott MacDonald]

It would yes.. or 465 which is used by some mail clients (Outlook?).

[SB]

Is it possible when this is implemented to get say a list of mailboxes which are sending through port 25 before enabling it?

or even a badge on the user account lists highlighting they are using power 25?

We have around 600 accounts (~1000 devices) migrated to Poste.io so far and it would be too much support to switch over and hope for the best!

[SH]

@shb1 no worries, I have no intention to break legacy networks (I am personaly supporting couple). This would be ON by default only for new installations and easily toggable.

[Scott MacDonald]

No worries SH... product has been excellent thus far.

[SH]

Already resolved