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["Silvers, Tim" <address@concealed>]

I wonder if you are bumping into Microsoft’s sending limits? If you have a lot of mailing lists, or they are quite active, or have enough subscribers, that could generate some significant volume. I am not sure how their sending limits apply to the Exchange connector. I am not an Exchange administrator.

 

Thought I’d mention it though, as it might be worth further investigation.

 

Tim

 

 

From: address@concealed <address@concealed> on behalf of Widerski, Betty <address@concealed>
Date: Wednesday, June 28, 2023 at 10:41 AM
To: address@concealed <address@concealed>
Subject: [External] [en@sympa] Microsoft Exchange connector outbound Sympa delays?

This message was sent from a non-IU address. Please exercise caution when clicking links or opening attachments from external sources.

 

This is a longshot question, as I expect few if any sites are doing this:

 

Our site has no anti-spam application for us to use with Sympa - we let Exchange handle analysis and lockdown of potentially compromised accounts. So we set up Sympa’s inbound and outbound email to route through the Exchange Connector as the best we could do for anti-spam.

 

We’ve recently gone live for real lists (that have more than just a few subscribers like our test lists had) and are finding that post delivery is being delayed by “connection timed out”. The posts do eventually go through after delays up to 45 minutes of deferred connections. My first thought was to tweak Sympa packet configs as we noticed this on lists of 1000+ subscribers - but then I found it was also happening with lists as small as 62 subscribers.

 

Sample maillog entry:

 

Jun 15 13:11:50 rhlists2 postfix/smtp[474298]: 3413C109DF6C: to=<address@concealed>, relay=none, delay=121, delays=0.19/60/60/0, dsn=4.4.1, status=deferred (connect to lists-hbs-edu.mail.protection.outlook.com[104.47.73.138]:25: Connection timed out)

Jun 15 13:11:50 rhlists2 postfix/smtp[474226]: connect to lists-hbs-edu.mail.protection.outlook.com[104.47.73.138]:25: Connection timed out

 

We’ve opened a case with Microsoft asking what is causing the timeouts to the connector. Has anyone else encountered this behavior with this routing config?

 

Thanks

Betty

 

Betty Widerski

Cloud & Server Engineering – HBS Information Technology

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