Has SMTP been blocked by o2 to 3rd party mail servers?

[Anonymous]

Hi all,

I have been using imap on my iphone for the past year and a half. In the last 6 months or so, something has changed whereby I am unable to send email (I can receive email) when I am on a mobile connection (Data/3G) however, when on WIFI my email sends fine.

My assumption is that o2 have blocked access via port 25, and port 587 to my mail server (heart internet).

It is frustrating that with no change in login details, i can send email over wifi, but as soon as I do not have wifi access - I am unable to reply to any emails, though I can still receive them. To my surprise this also happens overseas when using data roaming.

I tried setting up an o2 account so that i could use this as an outgoing mail server from my iphone - but alas, to no avail. that doesnt seem to be able to connect either.

This problem is currently occuring on:

my business partners iPhone 4GS - it occured on my 4G, and is now occuring on my new 5G - all have been on o2 contracts. I am therefore ruling out individual handsets.

It is also my understanding that by sending my mail from a o2 smtp - but having the email coming from mydomain.com - could trick some peoples email clients/mail servers into thinking my email is phishing or spam, and flag it accordingly. What has o2 changed? I never used to have this problem, does anyone have a working solution?

Many thanks in advance.

[Anonymous]

Hi Guys,

I'm very interested in this thread as I'm a Heart reseller and my customers have reported similar issues to me frequently over the last few years. 

I'm convinced that the problem is due to SMTP filtering policies at Heart.  From extensive testing with my clients handsets we've determined that the problem exists not just on o2 but also on some other networks that my customers use: o2/ee/virgin (maybe more but these three were tested) on GPRS/Edge/3G and 4g connections.  The reason why I think Heart are responsible is because my customers ARE able to send emails perfectly from their hotmail/yahoo/BT/EE/virgin accounts from the same handsets and connections that fail for their Heart accounts

Just like I_am_Jono, I have worked with Heart techs while they watch out for an SMTP connection to one of my accounts and they say that no connection attempt is made, but I'm suspecting that they have some kind of perimeter filtering that is using a PBL instead of the SBL or other blacklist by mistake. As the problem is intermittent then it might be that there is just one of their perimeter devices setup incorrectly. But trying to get Heart to investigate this is becoming very painful.

one of the major ball-aches with troubleshooting this is that error messages generates by the mobile handsets/tablets are woefully nondescriptive such as "connection failed" etc.  as part of the troubleshooting I did try tethering my laptop to my personal hotspot via a Edge connection and then used outlook to send data and i got frequent error messages to say that my connection was refused becasue my IP was on the PBL along with a link to the spamhaus.org PBL faq.  I argued with Heart that it wasnt appropriate for them to filter based on the PBL becasue all DHCP addresses should automatically be on the PBL by definition, so they should only filter based on the SBL, but by the time I got to speak to someone who knew enough about the filter listes the problem seemed to have gone away and couldn't be recreated.

If anyone has made any further progress then I'm all-ears and if I can help anyone with troubleshooting then please let me know.

Cheers,

Al

[Bambino]

O2 are shutting down their email servers. The only ones that still have any access to O2 mail are those who have O2 broadband, and after April, that will be shut down as well. This question has already been answered in this thread, but it appears you haven't read it thoroughly.

http://www.o2.co.uk/o2email