Tag Archives: email

Microsoft Outlook and Network Stored PST Files Don't Work

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Out of service
Photo From nic­olas­nova

I was recently called out to a new cli­ent site to stop a Microsoft Out­look 2010 cli­ent from crash­ing every time email was sent or received. It took a while to dis­cover the cause of the prob­lem because the issue was related to a con­fig­ur­a­tion that has not been sup­por­ted by Microsoft since Exchange Server 5.0 was released in 1997. So, not some­thing I’d expect to find any­one still using.

Don’t Store PST files on a net­work share

Accord­ing to Microsoft, among the con­sequences of using a net­work share to store pst files are:

When you store .pst files [on a net­work share], shares may stop respond­ing. This beha­vior may cause sev­eral client-side prob­lems, such as caus­ing Out­look to stop respond­ing or freez­ing desktops on cli­ent computers.

There is some fur­ther inform­a­tion and ana­lysis over on the tech­net blog, includ­ing addi­tional prob­lems caused on the server side, from way back in 2007!

Hope­fully this inform­a­tion will jog the memory of future troubleshoot­ers or give them another place to look when try­ing to solve prob­lems with Microsoft Outlook.

Stopping Bots From Blacklisting Your Mail Server

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Some of my cli­ents run a mail server on their local net­work enabling them to have full con­trol over their email sys­tem. Most Inter­net facing mail serv­ers will con­sult a black­list for all incom­ing email, com­par­ing the iden­tity of the send­ing server to known spam sources. When you are a busi­ness you abso­lutely do not want to have your mail server black­lis­ted as your cus­tom­ers mail serv­ers will simply refuse to receive email from your company.

Anger Bot!
Photo From Stick­Bus

A com­mon cause of black­list­ing, in my exper­i­ence, is when cli­ent PCs are infec­ted by mal­ware and become part of a bot­net. The own­ers of the bot­net then use the infec­ted machines to send out thou­sands of spam emails and its not long before this is noted and your con­nec­tion appears on a black­list, effect­ively pre­vent­ing your legit­im­ate email from get­ting to recipients.

To pre­vent black­list­ing I adopt these best prac­tices:

  1. Allow the local mail server to send email and block all other out­go­ing con­nec­tions on port 25 at the firewall
  2. Con­fig­ure the mail server to only accept con­nec­tions from authen­tic­ated mail clients.

Now only legit­im­ate users that are logged in to the mail server can send mail, any attempt by an infec­ted machine to con­tact an external mail server to send email is blocked at the fire­wall. If PCs then become infec­ted, the fire­wall logs will alert you to the out­go­ing con­nec­tion attempts on port 25 and the infec­tion can be dealt with.