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exchange relay

paul temporal
I am currently testing moving isp, i have made the required mx and reverse dns changes and everything checks out. I tried switching over and incoming mail is working fine but we are not sending. I quiclky changed back to the old isp and everything is fine. I noticed in my exchange 2010 server we are using as a send connector (on the organisational configuration/hub transport tabs) the old isp as a mail relay. I'm not familiar with this and have inherited this setup, should i simply disable the external relay to allow outgoing mail to flow?

Any help would be appreciated
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EE Solution Guide - Technical Dept Head
Most Valuable Expert 2017
HI Paul,
If you disable it will work without spamfiltering. It is not important though.

I suggest you disable it and create a new one. Ensure it is working fine. Once everything works as expected delete the old send connector.

Tom CieslikIT Engineer
Distinguished Expert 2017

If you have used SMART HOST before to send email through some external gateway with authentication and you going to create new connector now with direct send, make sure your external DNS has all appropriate entries, especially SRC (TXT) record with your MX and A host new IP.
If not, most server will reject your email.
Also your new Outbound connector must be configure to use MX record and Address space must be   SMTP   *    1
This is very simple to create by wizard if you have Exchange 2013
MASEE Solution Guide - Technical Dept Head
Most Valuable Expert 2017

I just remember when I read comment from Tom.
Do not forget to change IP in your SPF record.
David FavorFractional CTO
Distinguished Expert 2019

Relaying is very useful, else you have to maintain your entire sending flow for high deliverability.

My comments in https://www.experts-exchange.com/questions/29036679/AWS-EC2-mail-server.html cover some of the items you'll have to manage, if you don't use a relay service.

That said, the cheapest/easiest/fastest way to resolve this is use a reliable relay service. I've been using MailGun for sometime now + am converting all my hosting clients from other relay services over to MailGun.

As MAS suggested, you'll require changing your SFP record. MailGun provides you with all the DNS changes you'll require making + also provides a go/nogo test tool to verify all DNS changes you've made are correct.

MailGun's DNS docs are... concise/terse, so if you can't quite get this working, hire someone to get MailGun setup for you once + you'll have a working DNS template for future projects.