Hosted Exchange Issues

[swinnie]

Hi,

I have got around a dozen customers on Exchange 2010/2013 mailboxes with Simply Mail Solutions (SMS), and all but one are having no issues.

The most recent one is confusing, as the migration was no different to the 11 or so previous ones. Basically, some mail is not being delivered from a 'few' senders. Between myself and SMS Support we found that Kaspersky was filtering out mail and adding it to Blocked Senders, so I have temporarily turned off Junk Mail Filtering via the Web Mail. This seemed to return mail delivery to most of the senders that we were having issues with.

Now, we are aware of one sender that no matter who addresses mail to within our organisation, user1@, user2@ and so on... the mail never arrives, nor does he receive a mail rejection notice, delayed delivery etc. I found out the details for the email and asked SMS to check their server logs and the email never reached the SMS server. I have checked the MX Records for the domain and they remain unchanged (being managed by their web developer).

SMS suggested that I contact the senders mailserver administrator and get them to look at their logs, as they will have more details as to how the message was handled, where it was handled and any rejection messages that were delivered. I plan on doing this on Monday, as I know who runs the mailserver for the sender, but I'm unsure as the level of logs he will have access to.

What do you guys think, how would you proceed?

Thanks,

James

 

[Dogers]

If it's not even getting to you, you've exhausted what you can look at already. You need to find out where their server is sending messages destined to you! All mailservers worth their salt will have some system of logging or tracking what they're doing with emails - if the other end say it can't then they either don't know how to or are lying

The issue could be anything from a misconfigured mailserver to a stale DNS record somewhere. Knowing where their server is sending messages (which must be successfully delivered somewhere otherwise they should receive delayed messages) will lead deeper into the rabbit hole

 

[Caged]

This is a massive clutching-at-straws possibility, but I once had issues with mail delivery to a domain that had mail redirection set up by the domain registrar but then the MX records etc. were all changed to correctly deliver to an Exchange server. However, anybody who was using the mail hosting provided by the registrar (more of a web host I suppose) couldn't send mail, as someone tried to be clever by checking whether the domain was on their systems and instead of doing an MX lookup it was just processing the redirection rules.

Got it fixed once we got someone to understand what was going on. Unfortunately without logs there's not a lot you can do. What happens if you telnet to port 25 from the offenders network?