My MiaB is being blocked by Google's STMP server

Maintenance
1

Hi,
this morning I got a notification from the system status checks saying:

Outbound mail (SMTP port 25) seems to be blocked by your network. You will not be able to send any mail. Many residential networks block port 25 to prevent hijacked machines from being able to send spam. A quick connection test to Google’s mail server on port 25 failed.

I tried to send a mail to my gmail account which failed (I did not receive the mail and I didn’t get any message that the mail could not be delivered, either). Sending a mail to another email provider worked fine.
[Sending a mail from this second provider to my gmail account worked, so it seems not to be a general gmail related problem.]
I have no idea how to debug this problem. Any ideas?
Best,
Jan

Edit: My MiaB is hosted at Colorhost.de

2

happens to me too from last few hours ago:

Network -- Previously:
======================
✓  Outbound mail (SMTP port 25) is not blocked.

Network -- Currently:
=====================
✖  Outbound mail (SMTP port 25) seems to be blocked by your network. 
   You will not be able to send any mail. Many residential networks 
   block port 25 to prevent hijacked machines from being able to send
   spam. A quick connection test to Google's mail server on port 25 
   failed.

Knowing I have 2 servers running (one at DO running v0.13b in production and the other one at Vultr running the current master version as test/ development environment) and seeing the issue has been reported by their (both) server status checks at +/- same time interval … perhaps the issue is not because my MiaB configs. that till yesterday reported all as ‘green validated’ under their respective status checks but the google server fails to respond…!?

Network ✖
Outbound mail (SMTP port 25) seems to be blocked by your network. You will not be able to send any mail. Many residential networks block port 25 to prevent jackedmachines from being able to send spam. A quick connection test to Google's mail server on port 25 failed.

Note: I verified mail sending and receiving are correctly working so far, too

Any feedback will be very welcome!

3

I’ve just got this notification too, hosted on linode in the UK.

4

A friend who has a self-configured (the hard way) mail server just tried to send me a test mail to my gmail account. That did not work either.
It seems that this is not related to MiaB but to Google blocking small (?) mail servers.

5

The error message is merely a network connectivity test. It doesn’t attempt mail submission. The idea is to check if your local network is configured properly, using Google as a random mail server to test against.

Maybe Google had a brief outage.

6

Now everything is fine again.
If sending a mail from my universities’ mail server to my gmail address failed, the brief outage would have been my first guess. But this worked all the time. Only the mails from my personal MiaB were not delivered.
Anyway, it works. I’m happy.

7

This error message likely has nothing to do with deliverability.

8

But at least this time it correlated quite well.

9

Thanks for your confirmation… BTW, my (both) MiaB servers stopped reporting mentioned issue about ‘Outbound mail (SMTP port 25) seems to be blocked by your network.’ few hours ago through their respective status checks.