[BlueOnyx:21201] Re: Outbound sendmail port

[Colin Jack]

Hi Chris,

> -----Original Message-----
> From: Blueonyx [mailto:blueonyx-bounces at mail.blueonyx.it] On Behalf Of Chris
> Gebhardt - VIRTBIZ Internet
> Sent: 18 July 2017 14:54
> To: blueonyx at mail.blueonyx.it
> Subject: [BlueOnyx:21199] Re: Outbound sendmail port
> 
> Hi Colin,
> 
> On 7/18/2017 6:53 AM, Colin Jack wrote:
> > Is it possible to change the outbound sendmail port to 587 from 25 via the
> GUI?
> > We are testing a new relay server and they will only accept mail on 587.
> 
> To make sure I've got you clearly, you're saying that you want all outbound
> email from the server to 587?  That won't work at all as that's not how SMTP is
> designed.
> 
> 587 is submission port, and should only accept email from authenticated users
> (ie: a username & password).
> 
> Relay from server to server is always performed on 25.

This is an anti-spam/AV relay. They will only accept mail relayed on the submission port:

-- quote --

Trial users:

    SMTP Hostname: smtp-trial.antispamcloud.com

    Port: 587

-- end --

It is possible to set it in sendmail.cf (Mrelay) but not via the GUI.

As you say - normal communication between SMTP servers is on port 25, but in this case we are relaying, not sending direct to other servers.

Colin