I switched from ADSL2 to VDSL around noon yesterday, a 2 minute job as I already master spitter in place, I'm 500m from the cabinet, VDSL modem already configured, just needed Telecom to switch over at their end really. I have a static IP address as I have my own server for routing, hosting email, http etc. After their tech was on the phone for 30 minutes arranging the switch over, all seemed good with 40Mb/12Mb down/up. However after switching to VDSL, it appeared that inbound (but not outbourd) port 25 was blocked by Telecom (I wasn't getting external emails). I have port 587 in use too, but it appeared that wasn't being used. So I could send email, but nothing external was arriving. I'm still using smtp.xtra.co.nz, as I don't think send.xtra.co.nz works for me (because I would need to authenticate lots of email addresses).
Of course I fluffed around with all the modem settings first trying to see if I was doing something wrong, as that was really the only thing that had changed. After an hour or so of that I called the beloved Telecom Broadband Helpdesk
They suggested all the usual irrelevant rubbish, which in my experience you have to just politely point out is irrelevant rubbish before you can get escalated, things like resetting my modem to the factory defaults, turning off my firewall (the modem is in bridge mode connected to an Ubuntu server running iptables and postfix), or powering it off and on (computer and modem, with the classic leave it off for 10 minutes in between suggestion), or using webmail to access my email (no, they really didn't get my setup). The real rub was the first time I called (at about 2pm) they insisted they couldn't do anything until after 7pm when the install ticket closed, with a dim hope that because everything is not finished until that time, so it might come right before then. When I called back at 7pm I eventually got escalated all the way to level 2 (woohoo), to be told the only ones who could unblock port 25 worked business hours (oh joy), and to fill out the web form, which politely says it can take up to 2 days to be actioned), or to call my local Business Hub the next day (who I did call this morning, and they just transferred me back to level 1 broadband help desk, despite me asking if I could go stright to someone a bit more technical)
But finally this morning the front line support person that I spoke to actually understood the problem (having read the history), told me he could contact someone to deal with it, took my mobile so he could call me back ("in case I wanted to go out" - thoughtful is a good sign), called back 20 minutes later and said they were working on it, and about 40 minutes after that email started arriving. I got all my test messages I sent myself throughout yesterday while trying to debug the problem, so the good news is they were queued not dropped. Still haven't heard back from Telecom 2 hours later, but at least we got there in the end.
I hope this helps someone else ... because I could send email and not receive it it seemed unlikely at first that this was just a port 25 block implemented mostly the wrong way round (incoming but not outgoing), especially with postfix listening on both ports 587 and 25, so it was a bit of a goose chase, with not much help from Telecom until this morning.