Question : Would the disabling the open relay affect the sending email on mobile phone (POP)

The system is: Exchange 2003
The open relay in SMTP has recently disabled. Would this affect the sending from the mobile phone (the email account on the mobile was set as POP account)
At the moment, I can check incoming emails, but I CANNOT send the email out via the mobile phone.

1. Maybe disabling the open relay prevent me from sending the email via the mobile phone?? If so what's the alternative ?
2. Do I understand correctly ? as I understand that sending email from mobile phone will require the open relay with my Exchange  as when "send" is pressed, the mobile will connect to the Exchange (SMTP server) and then got rejected as the IP of the mobile phone (which is my home WIFI) has not included in the 'allow list to relay through SMTP?
3. However, on the Exchange  I do checked on something like "allow the authenticated (with username and password) to use relay  disregard the allowed list below) then this should allow my mobile phone to send email though SMTP eventhough I have not added the IP of my mobile phone into the allow list??

Please clarify.

Thanks

Answer : Would the disabling the open relay affect the sending email on mobile phone (POP)

After changing the authentication method, you have to bounce the POP virtual server for the change to take effect.  No need to reboot the whole exchange server, just stop / restart the POP3 virtual server and I bet that fixes your problem.  Unless you have a cert on there or the smtp server is requiring TLS or something like that.  

As for your smtp server showing sessions, there are security settings you can apply to help with that, but they won't do any good if the outside party has compromised a valid password.  One thing to look at, verify in those sessions how long they've been connected for one thing - if it's just a few seconds and then they're getting bounced, they're just fishing around and not doing any good.  If you see someone connected for 10 min, for example, that is indeed a problem.

But you're right, first thing's first.  Lets get your email flowing properly, and then we'll go from there.