Originally posted by JonRohan
Why is it not encouraged? It will slow the server down?
All our clients have the server names as smtp.mydomain.com In outlook.
This might help you a little:
WHY DOES MY WEB HOST TELL ME TO USE MY ISP's SMTP?
The problem is with Abuse Violations. Most web hosts nowadays operate on a "shared hosting" environment. This means that there are more than one domain hosted on a single physical web server. All the resources, including the IP addresses, are shared. Now let's say domain1.com is a great customer, but domain2.com is a SPAMMER! He uses the web server's SMTP to send out hundreds of thousands of unsolicited emails before being caught, but by that time it is too late. Damage is already done. More than likely your IP address has been "Blacklisted" by SpamCop, SpamHaus, or other DNSBL's that help prevent SPAM from reaching good email accounts around the world. Once your IP address is Blacklisted, it has a negative impact on ALL the accounts on your shared web server.
If the perpetrator had been normal and used his ISP's SMTP, you would have prevented the situation totally. Even if he spoofs his (or another domain) to the offending messages, the DNSBLs can see right through it in most cases. If the ISP bans the user then that is fine, it is no problem of yours as a host. Additionally (and most importantly) if the problem involves legal issues, YOUR WEB SERVER is the last easily tracable location of the offense!
BUT CANT THE USER JUST USE A WEB SCRIPT LIKE SENDMAIL OR WEBMAIL TO SEND THROUGH THE SERVER?
Yes, but in that case all the actions will be regulated by the mail server and logged and timestampped in log files if the server is properly configured using Suexec, etc..
BUT WILL ALL MYDOMAINNAME.COM ACCOUNTS WORK IF I USE MY ISP SMTP IN OUTLOOK?
Yes, I did it on mine. I am not an outlook expert by any means, but it just works, it is really cool...
When I receive an email from lets say webmaster(at)domain1.com, I just click REPLY and outlook knows to send it "from" webmaster(at)domain1.com...
ditto that for domain2.com, domain3.com and so on. All use the SMTP from the ISP.
It is transparent unless someone views the full mail headers and traces that end IP. If someone is not cool with that then 99% they are doing something very shady. That is the theory in a nutshell.
(FYI we will be adding this and other server management
FAQs here soon
