BTConnect and Dynamic IP SMTP server problems.

So, I've got Exim working really nicely... I think.

I've got a "dynamic" IP address from my BTConnect business broadband connection. This means that I have trouble connecting directly to SMTP servers from my server because their reverse lookup of my name doesn't match... i.e. it resolves to a dynamic BT address, and some SMTP servers are rightfully suspicious of that and punt me away.

So I've configured Exim to relay to mail.btconnect.com. This works because I've registered my 2 domain names with them, and their mail relay will accept stuff coming from those domains.

However, I also forward e-mail for my sister, and have a couple of little mailing lists configured, and these get bounced because I retain the name of the original sender on my outgoing forwards.

Hmmm. This should be solvable by authenticating myself on BT's mail server.

Trawl of the BT Broadband site tells me that:

1: BT Connect, (the business one) doesn't allow SMTP authentication:

 # telnet mail.btconnect.com 25
Trying 194.73.73.217...
Connected to mail.btconnect.com.
Escape character is '\^]'.
220 C2bthomr06.btconnect.com ESMTP Mirapoint 3.7.4b-GA; Tue, 21 Nov 2006 17:50:20 GMT
ehlo <mydomain>
250-C2bthomr06.btconnect.com Hello host<nnn>.btcentralplus.com [xx.yy.zz.aa], pleased to meet you
250-8BITMIME
250-SIZE 52428800
250-DSN
250-ETRN
250 HELP

2: BTInternet, (the consumer one) does:

# telnet mail.btinternet.com 25
Trying 217.146.188.192...
Connected to pop-smtp1-f.bt.mail.vip.ird.yahoo.com.
Escape character is '\^]'.
220 smtp808.mail.ird.yahoo.com ESMTP
ehlo <mydomain>
250-smtp808.mail.ird.yahoo.com
250-AUTH LOGIN PLAIN XYMCOOKIE
250-PIPELINING
250 8BITMIME

Phone call to the BTConnect helpline. They understood my problem. Were slightly sympathetic, but confirmed that the only way to send none BT domain e-mail via their BTConnect server was by pre-registering EVERY domain with them. Clearly impractical. (Heck, I don't know who's going to send my sister an e-mail)

Phone call to the BTInternet helpline. I used to have an account. It was suspended due to lack of use. Got it re-instated. But they said I had to dial up at least once every 6 months to keep it going. I don't have a dialer at home, I'm bound to forget, and I'm not crazy about plain text authentication. But I reconfigured Exim to use mail.btinternet.com as my smart relay, and started authenticating. Thankfully, my sister's e-mail stopped bouncing at that point.

I wasn't particularly happy with the solution. I had a couple of long term fixes in mind:

  1. Convert to Static IP from BT, which means I could register my name in the rev-arpa tables. Costs money. (Though they should really do it for free, my "dynamic" IP address has not changed in about 3 months.)
  2. Sign up for BTInternet's premium e-mail solution @ 1.50 a month, which means I could continue to use the mail.btinternet.com mailserver. Costs money, and not happy with plaintext auth.
  3. Something Else.

I ended up doing something else.  I had a rant about this to one of my friends who happens to be my secondary MX (for when I break my machine), and he chuckled and reminded me that when he set the MX up, including my account on his server he also enabled encrypted SMTP authentication for me. All I needed to to is point at his server in the first place. (Which I am now doing)

The only other thing I want to do is set Exim up so that outgoing mail from my domain sent to mail.btconnect.com, otherwise to use my friend's mailserver. I know it's possible, I just need to write the rules. Here they are:

# Use this one for mail originating from my domain so I don't overload smart_route2
smart_route1:
driver = manualroute
domains = !+local_domains
senders = \*@<mydomain>
transport = remote_smtp
route_list = \* mail.btconnect.com

# Use this one for mail NOT originating from my domain. (i.e. mailing list/alias expansion)
smart_route2:
driver = manualroute
domains = !+local_domains
transport = remote_smtp
route_list = \* <my friend's smtp server>

(obviously <mydomain> is my actual domain)

Exim is COOL.

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