I would like to ask for advice about SMTP Servers.
I'd like to setup a small and simple server for a school project for which I need to send (or mock send) emails to a small amount of recipients.
So I need a simple, lightweight and Windows 10 compatible SMTP server.
I've already tried hMailServer but it didn't work, though I don't know why.
It had also messed with my OpenVPN configuration and I needed to reinstall it to have VPN tunelling working again.
Thank you in advance for any piece of advice.
Related
My Ubuntu based webserver needs to occasionally send emails. My python code is:
withsmtplib.SMTP('smtp-relay.gmail.com', 587, 'mydomain.com') as s:
s.sendmail(fromaddr, toaddr, msg.as_string())
s.quit()
I have
a Google workspace account
am using IP authentication (not SMTP auth)
my staging and production servers added as trusted IPs (staging is
local, production is cloud)
This setup had been working fine for 6+ months.
Two days ago I upgraded Ubuntu from 20LTS to 22LTS and python 3.8 to 3.10. Now the email is working fine on the staging server, but production keeps throwing:
Invalid credentials for relay [...]. The IP\n5.7.1 address you've registered in your G Suite SMTP Relay
service doesn't\n5.7.7 match domain of the account this email is being sent from. If you are\n5.7.1 trying to
relay mail from a domain that isn't registered under your G\n5.7.1 Suite account or has empty envelope-from,
you must configure your\n5.7.1 mail server either to use SMTP AUTH to identify the sending domain or\n5.7.1 to
present one of your domain names in the HELO or EHLO command. For\n5.7.1 more information, please visit
https://support.google.com/a/answer/6140680#invalidcred ...
Any suggestions?
Edit 1:
I fired up my old ubuntu server in the cloud. I added its new IP as trusted on Google. The email worked fine. I can think of only three possibilities
Google somehow recognizes and trusts requests coming from the old
device (even though it now has a different IP)
Linode is somehow not sending the correct IP address from my new
server
Something broke during the Ubuntu upgrade
I find each of the 3 possibilities quite bizarre and unbelievable at this point, but I'll keep researching.
PS: Three factoids that may/may not be relevant:
I upgraded the staging server in place. For production I spun a new
instance, made sure everything else was working fine (except
email) and then transferred IP from the existing instance to new
When I log in to my google admin account to edit trusted IP list, my
IP is the same as staging server. I don't think I have the same
option for production, since it's an Ubuntu server I manage through SSH
I found some comments online (none in official documentation), that
the reverse DNS needs to be setup before Google would relay anything.
I set up the entry about 20 hours ago for production, but still
getting the same error. And for my staging server, I don't have rDNS
and it still sends emails (it's accessible from the internet, but I
don't have a static IP)
PPS:
The sender email is someuser#mydomain.com (not #gmail.com)
The production server is hosted on linode.com
This post comes close
to discussing a similar situation, but that is focused more on
signing in. My setup uses IP authentication, not SMTP auth. Plus it was working fine until Friday (8/12)
It turned out to be a really frustrating issue. My best guess is that Linode's Ubuntu 22.04 repository has issues. We were thinking of migrating to AWS anyway, this gave us a strong impetus.
Anyway, here are some tips from my experience that a future reader might be able to benefit from
When you're using IP authentication for Google's SMTP relay, the updates are fairly quick. I ended up spinning at least 5 instances with 5 different IPs, and each time Google was able to trust my IP within 2-3 seconds (after I updated in workspace console)
Google didn't care about my reverse DNS entries. I had read some comments online that Google wouldn't relay without rDNS, but I didn't face any such problems (at least not any rDNS I was setting. The ISP or the cloud provider have a default entry, that was good enough - if Google was even looking for it). This one was particularly problematic because that information can take hours to propagate, and I kept thinking maybe my code will start to work tomorrow.
The error message I received from Google was pretty uninformative. I contacted Google support to see if they have access to anything more meaningful on the server side. They didn't - it was a waste of time
It was somewhat helpful to run a fake SMTP server to see what my client was sending. I got it from this post. I ran it for a setup that was working and one that wasn't. In my case, the communication received was identical. Though in hindsight maybe I would've seen some differences if I ran it on a remote server.
python -m smtpd -n -d -c DebuggingServer localhost:2500
Old linux user here; but only recently started using Google Cloud solutions to create a few VM instances running CentOS. Works great and have been using them for a few years successfully.
I am adding some new functions and I would like to be able to get emails that normally go to root to be sent to me.
In the past, I simply added a line in /etc/aliases at the end of
root: myemail#gsuitedomain.com
This worked well as most of the boxes that I managed were inside a network where I also controlled the local mail server and could just send through it.
It appears that I need to setup some sort of relay using G-Suite?
Is that the right path?
Also, I really don't want to relay the email. I just want to send it to one of the G-Suite accounts. So, no real relaying needed.
Can someone direct me in the right direction for the easiest path to accomplish this?
Thank you for your help,
Tamer
GCP by default blocks all outbound traffic on port 25 so you have to use different one. You can read about it in more detail in the GCE documentation.
In my opinion you will have to run sendmail, postfix or anything else to send emails out but you have to configure them to some other port than 25.
I have just had to re-image my server and for some reason, when I do a test connection in outlook, it errors on both send/receive with could not connect to server.
I have checked that both postfix and courier-imap are running on the server and have restarted both just to make sure. I am using plesk 12 and have setup users for the email system, so would appreciate some guidance as to how I can troubleshoot this. Many thanks
SOLVED
Reset iptables all good now
I would like to be able to send emails in command line and in bash scripts (e.g., to get notifications about running simulations on my computer). There are apparently different options to do that, but all seem to rely on postfix. However, as far as I understand it, postfix is a full email client to send and receive emails. In my case, I am just interested in sending emails.
I am particularly worrying about security issues and I don't want to open any doors on my system by installing one of these programs.
Any advice on how to configure postfix to only allow outgoing emails and to block anything else to avoid any threats? Or any other ideas to send emails securely?
Many thanks for your help!
PS: Running Ubuntu 14.04.01 LTS.
I do web development from my ubuntu server, ubuntu is running in virtualbox in my windows 7. What do I need to configure inside of ubuntu in order to send email to any public domain, gmail.com for example? I need this set up for testing email templates etc... Thanks, Jaro.
For testing email on the ubuntu machine, the best way is to create a local account and use email like account#localhost.
It is not a good test otherwise if you want to send mail directly from your system, as many ISPs are not allowing SMTP traffic over broadband DSL, e.g. my provider THREE in UK doesnt allow it, as well many big email companies will reject emails coming from broadband subnets.
Another way would be deploying the mail server, which is complex, also you can test your app at any free hosting provider too.
Basically testing email is nothing close to being simple and to test it properly, you need a production system with mail fully setup and working, whitelisted, not on DSL and so on.