Mailcow over VPN not sending emails.

apoorv569

esackbauer So I need a relay server? It won’t work with it in my case?

esackbauer

You need a relay server. Its all explained in that link.
You can host one yourself on a VPS, or you can use Sendgrid or Mailgun which have a free tier.

apoorv569

esackbauer Do you use a relay server as well? Asking because you said you also self host mailcow at home. Or is it specific to my scenario?

esackbauer

apoorv569 Do you use a relay server as well?

Yes I do.

apoorv569 Or is it specific to my scenario?

No.

apoorv569

esackbauer The person in the post you shared with me, mentions that I need to add relay info in the Routing page in mailcow admin UI using SASL. I don’t remember setting up anything called SASL. I don’t think they are using the docker version either.

The HOST would just be mail.MY_DOMAIN I guess and would the username and password be the current mailbox I have? admin@MY_DOMAIN the password for this mailbox?

They also talk about making sure postfix is running in chroot, not sure what that means? like it has write access?

Is a SMTP relay server, just another Postfix server?

Sorry as I mentioned I am new to mail servers, but willing to learn and understand, at least the required bits.

esackbauer

Oh boy you have to learn a lot… Mail servers are among the most complicated things to understand and properly operate. Mailcow makes just the installation easy, not the operations or configuration if you have nonstandard requirements.
You should really start with simple setup and use existing relay servers like mailgun or Sendgrid. Or pay for a static IP (if your ISP offers that) or even better install mailcow completely on a VPS.

Actually SASL is not necessarily needed, if you can lock down postfix on VPS (which is then your relay server), to not allow other parties to send spam. Can do on firewall level. That again depends on your abilities to configure firewalls and your hoster and/or your operating system.

apoorv569 Is a SMTP relay server, just another Postfix server?

SMTP is the protocol, not a server. Postfix is the server software (there are others like Exim) that speaks SMTP and is a so called Mail Transfer Agent (MTA). Please learn the differences between MTA and something like Dovecot. It makes the whole thing more clear.

apoorv569

esackbauer I see. So if I install mailcow on the VPS directly, I don’t need to do anything extra? just start the containers and it would work? This mail server is for my personal use only BTW, I will be using this for my other self hosted services, for things like, if a user requests for password reset on Nextcloud, or alerts from various self hosted services etc. I won’t be using this for public use. Do you think 1 core, 1G RAM and 25G disk space is enough to host mailcow for such a use case? as the VPS I rent is shared CPU one.

esackbauer

apoorv569 , I don’t need to do anything extra? just start the containers and it would work?

Yes. Maybe if the hoster has a firewall in front of it you need to open the ports there.

apoorv569 Do you think 1 core, 1G RAM and 25G disk space is enough to host mailcow for such a use case?

Mailcow is a groupware and so much more than just a postfix as MTA.
If you want something so basic, mailcow is actually too much for you, it needs at least 2 cores and 6 GB to work properly.
4 GB might be enough if you disable SOGo and ClamAV and Solr.
But if you do so you are better off using a different solution like Docker-mailserver or mailu.

apoorv569

esackbauer I see. Yes I actually don’t really need a full blown email suite, just a lightweight email server that can send users alert and password reset links etc..

So these 2 projects you mentioned they are much lightweight?

apoorv569

esackbauer OK, so trying to make all work for 2 days now. Haven’t gotten it to work. At one point used Luke Smith's emailwiz script to install postfix and dovecot directly on VPS which kind of worked, I could receive mail but could not send mail.

I opened a ticket on DigitalOcean where I have rented the VPS, they said port 25 is blocked and cannot be opened.
Now I wonder do I need to this port 25, if like I host like a relay server on VPS? Can I not change port 25 to something else in general?
They suggested I use SendGrid which they have partnership with as a relay.
In my case sending email is more important than receiving it. So its kind of useless if I can’t send mail.
I want to avoid third-party apps if possible, as it kind of defeats the purpose of self hosting.

What do you think?

esackbauer

apoorv569 Now I wonder do I need to this port 25,

You need port 25 outgoing. Otherwise it will not be able to talk to any other mail server.

apoorv569

esackbauer So I can’t avoid port 25 and because VPS can’t open it for me, I am out of luck for self hosting mail server?

I heard you can change port 25 to 587 or something.. something like, changing the link starting with smtp inet to 587 inet. is that not true?

There exact words to me are,

The suggestion was to use SMTP mail relay at Droplet on port 587 and when you send mail to any external mail servers from home it will be using port 25.

and gave me this link as a reference, https://reintech.io/blog/configuring-mail-relay-sendmail-ubuntu-20-04

I am very confused, I thought if you can’t access port 25 that’s when you use a relay, but looks like even a relay needs port 25?

If port 25 is required no matter if its relay or not, how would someone use GMail as relay for example?

esackbauer

apoorv569 but looks like even a relay needs port 25?

You sure need to learn a lot about SMTP and firewalls. Firewall rules have a source and destination. So it can apply to incoming and/or outgoing traffic. Outgoing Port 25 is what providers are blocking.
We posted already several solutions here in this thread, please pick one.
Sorry you have to learn the basics for running servers elsewhere. This is a mailcow specific forum.

DocFraggle

LMGTFY

https://sa.ndeep.me/post/how-to-use-sendgrid-as-an-smtp-relay-in-mailcow/

Port 587