Check your email account settings.
If you just configured your mail account and are directly presented with a send/receive error, you should start with verifying if your account settings are correct. You can get this information from your ISP or email administrator. Settings for several large free email providers can be found here.
When you are trying to send a message from another network than the network where the mailbox is located (for instance, from a hotel or a wifi hotspot, then you need to enable authentication for the configured SMTP server as well.
When Outlook worked before and you’re suddenly presented with send/receive errors, it is still good practice to verify your account settings and make sure that they are current. For example, several ISPs have increased their email security settings which could require you to enable SSL or make port changes. Also, sometimes they have merged with other ISPs and decommission the old account settings over time requiring you to make changes.
Trying your account settings on another computer or creating an additional mail profile for testing could help you determining if it is an issue with your current account configuration settings.
Disable virus scanner integration.
Virus scanners which integrates themselves with Outlook are a known source of causing all sorts of send receive issues. For instance, the following time-out issues are often a result of this;
-The operation timed out waiting for a response from the receiving (POP) server
-A time-out occurred while communicating with the server
Other issues that are often caused by having a virus scanner integrated with Outlook are;
-Outlook being very slow in collecting your email
-Messages ending up stuck in your Outbox (also see below)
-Messages being sent but never received
-Sending or receiving blank messages
-General message corruption
Disabling your virus scanner’s integration with Outlook does not compromise your security as you’d still be sufficiently protected by the on-access scanner part of the virus scanner. For more details see; Disable virus scanner integration?
Check your firewall settings.
Firewalls can block incoming and outgoing traffic so make sure that Outlook and/or the required ports for email are listed as an exception to go through.
If you are presented with send/receive errors after updating Outlook, you probably need to reconfigure your firewall to re-allow Outlook to pass-through again. This is because several firewall solutions (such as ZoneAlarm) verify via a hash that it is indeed the correct outlook.exe that is trying to pass through the firewall and not some virus which named itself outlook.exe. Since with some updates the outlook.exe gets updated as well, you’ll need to accept it as safe again. You can find more information about this in the manual of your firewall solution.
Issues with add-ins
Aside from virus scanners, there could be other add-ins installed which integrate itself with the send/receive process of Outlook. Loading Outlook in Safe Mode is a good first step to see if add-ins are indeed the cause of the issues.
To further troubleshoot add-ins, manually disable each of them and re-enable them one-by-one to find the culprit.
Check data store integrity
If there are issues with the delivery location (your Outlook mailbox), then this could result in send/receive issues. Checking the integrity of your delivery location can be done with scanpst.exe or scanost.exe (depending on your mail account type). In some cases you’ll need to run the pst2gb tool when the data store is full.
If you are using an Exchange account, then you could also try it with Cached Exchange Mode disabled and see if it works correctly now. If it does, rename the ost-file to .old and have Outlook rebuild the ost-file or verify that the configured location for the ost-file in your account settings is valid.
Stuck message or hidden read receipt
A stuck message is also often a source of having send/receive issues. While it is easy enough to spot a message stuck in your Outbox, in some cases the stuck message can be a Read Receipt which are hidden messages and thus much harder to recognize as the issues and to delete.
Other send/receive issues
Below is a short list of other common send/receive issues which you could encounter but which are not directly identified by a send/receive error.
In some cases Outlook can not remember your password for your mail account which results in being prompted for it.
When you receive multiple copies of a message or receiving the same message(s) over and over again see this guide.
Rules not being processed automatically
When you have rules configured but they are not executed automatically when you receive new emails, see this guide.
No automatic send/receive upon starting Outlook or cannot edit Send/Receive settings.
In those cases, reset your srs-file by renaming it to .old.
Bug in update KB2412171 for Outlook 2007
The original version of update KB2412171 for Outlook 2007 caused several authentication issues namely with SPA and SSL.
Considering this issue has been fixed quite a while ago, you probably have installed the latest version already via Microsoft Update (recommended) but it’s still worth checking if you are fully up-to-date (Service Pack 3 for Office 2007 fixes it as well). You can also download the update here and apply it manually.
More information: Issues with Outlook 2007 after applying KB2412171