Postfix, email server, ISP blocks port 25 quesiton

I hope I posted this to the right area. I didn’t think it would be directly related to virtualmin, and I searched but couldn’t find anything, but here goes. My ISP blocks port 25. Everything with my Virtualmin is working wicked otherwise. Is there a way to use my ISP’s mail servers to act as a go between from my server at home to the internet etc? Basically I want to have and have my clients check their email through usermin etc. Or use Outlook and others. But I can’t directly from home because of this port 25 issue. Does anyone know how to do this, if it is possible? Thanks!


If I understand correctly – it sounds like you have a server running at home, and you want to be able to have your clients connect from where ever they are on the Net to your home-based server.

And indeed, a lot of ISP’s do block port 25 these days.

To configure your server at home to be able to send mail from your server out to the Internet, you’ll probably want to use a “relay_host”. You can set that up with:

  • Log into the control panel
  • Choose "Webmin" at the top-left
  • Click Servers
  • Click Postfix Mail Server
  • Then choose General Options

Once there, you’ll see “Send outgoing mail via host” – you can supply your ISP’s mail server there.

Now, that only solves the outbound port 25 issue. There’s still the problem of incoming port 25 – when your clients try to connect to your servers port 25, your ISP may still be blocking that.

What you’ll probably need to do there is have your clients use a form of SMTP authentication that uses a port other than 25.

This document here should get you started:,com_openwiki/Itemid,48/id,configuring_encrypted_smtps/

Have a good one,

That worked perfectly! Thanks a million. In regards to receiving email, you are right my ISP blocks 25 there as well. I checked out the link you had there. Is that what I need to do for sure? I have googled a few things and I’ve found a couple of sites that say the server can listen on another port? Or the port is redirected or something like that? I’m not really sure if what I’m saying is either accurate or making sense at all. Thanks again!

Heh, I completely forgot about actually receiving email as I typed the above! The blocked in-bound SMTP is going to be a big issue :slight_smile:

While you can certainly have your mail server listen on an alternate port, sending mail servers would need to be configured to speak to you on that particular port.

That is, all but a handful of servers would be unable to send you emails :-/

If you’re pretty set on running your server from home, the best I can think of is that you might be able to convince someone you know with a server on the Net to act as a relay for your domains, and then send (relay) those emails to you on your alternate port.

However, places like offer VPS’s starting at $20, that might be a better all-around solution. That, or some ISP’s will lift the SMTP restriction if you give them a few extra bucks to consider you a “business” user.

Hmm. Okay, so receiving email is going to be trouble. There isn’t a way of using an ISP’s incoming server just like for the outgoing server? I always thought that ISP’s block outgoing more so than incoming, because they don’t want people to spam or have their computers used as spam servers. But getting emails, to me at least, seems less of a spam issue. Maybe I’m wrong. I’ve been hosting with the planet for a while, but only have like 4 clients and the cost has been way too high for such low bandwidth, so hence, I’m hosting from home. Thanks again.

Unfortunately, coming up with ways to receive email isn’t quite as easy as sending it. While anyone running a mail server (including your ISP) is capable of setting it up to relay email to you, the trick is convincing them to do so :slight_smile: There’s some effort involved in setting that up, and all but the most flexible of ISP’s aren’t going to do that.

As far as why they block incoming SMTP? I’ve often seen that combined with blocking incoming HTTP, and it’s easy to write that off as them wanting you to buy their business package before you can run a server. Whether that’s designed to help their bottom line or because they don’t trust consumers to lock down their machines is left for a future debate :wink:

I see your point. My ISP does have a business package, which cost more obviously. It does come with at least a static IP address, and they probably (I hope) have port 25 open. I’ll have to do some thinking. Is there any other options available to me? Is there a way to route email to an outside email address? For instance if you had a gmail account or something? That doesn’t really make sense though either. Hmm, I’ll have to see what I can do.

Well, one thought that comes to mind is this Dreamhost blog posting I read recently:

Dreamhost goes as far as saying that they’re encouraging their hosting customers to use Gmail rather than Dreamhost’s own mail service. They point out that Gmail does it better and cheaper.

Gmail allows you to setup an email account (or accounts) using your own domain name, you don’t have to use theirs. So you can have web traffic going to your own server, but email going to Gmail’s servers.

Just a thought!

That’s amazing. If I’m reading that right, and I’m pretty sure I am, you can have an email address with your own domain, but use gmail instead. I didn’t look too far into it yet, but I checked out google’s gmail, and they say that right on the feature page. I’m not sure how it works yet, but that’ll work perfectly for me. I’m going to check it out. Thanks again for the advice!

Before anybody migrates to Google Apps for mail they should spend some time reading here.

Apps for your domain is not perfect, but I’ve got one of my old domains setup to receive mail via gmail–if I used the domain heavily, I’d want it under my control, but since I only check it once a week and almost never send mail, it works out fine. For a few bucks per year it’s a really good alternative if you don’t want to think about it.

There are some things about Gmail that truly kick ass (and I’m not just saying that because my girlfriend is on the Gmail team at Google), though:

Good/fast search. No other mail client I’m aware of is as good at search (which seems obvious, though the problem of searching mail is quite different from searching the web, and pagerank is a meaningless algorithm for mail search).

Nice threading. This is something I liked in mail clients I’ve used in the past, but it became passe for some reason. Gmail is bringing it back into popularity. We’ll be adding threaded discussions in Usermin in the not too distant future.

Fast, for a web UI. It’s actually generally faster than Thunderbird for most tasks for about the same sized mailbox. Some things are more time-intensive (paging through large volumes of mail for example), but others are perfectly acceptable.

And, of course, you can access it via POP and IMAP, so even if you don’t like the UI, you can use another interface.

Before anyone does anything look at – They offer mail redirection to any port for free :slight_smile:

That’s cool too, but its just a free trial by the looks of things. Although, the price is really cheap and that’s great, for me I think the gmail option is the best. But for others that want to handle more of the email aspects, that’s a great option.

You didn’t look –

Basic Free!

* Limited to 1MB of incoming mail or 50 messages per day.
* Test drive our services before you upgrade!

I was having almost the same problem. The high speed internet providers in my area had said that the port could not be unblocked because of the content going through my neighborhood. I didn’t really understand what this meant so after many long nights on the phone with my ISP, they have helped me open port 25.

Thanks for the great response.

i had read this post, first part, annd i solved the problem with the outgoing email, but for incoming email the link above do not work, this one,com_openwiki/Itemid,48/id,configuring_encrypted_smtps/ and this is not the right post please help me to solve the problem with incoming e-mails. thanks