Mail Delivery Failures Issue
The most common problem that plagues mail servers is failure to receive or send email. Web masters are well aware that the causes of such problems are very minor and can be easily rectified.
Firstly, mail servers could be overwhelmed with a host of unnecessary scripts and applications that affect their basic function of mail delivery. The performance of your mail server depends on its ability to devote all its resources to mail delivery and when other applications take up these resources, you will keep getting errors with emails not coming in or going out.
Mail Delivery Failure Reason
The default port for email servers is port 25- any problems with this port or it being blocked can cause mail delivery failure. Also, this port is designed for a single mail server so you have to be extra careful while configuring your email server.
Mail server machines should not be over worked or over burdened. This is especially true of enterprise servers. The machine might simply overheat and crash resulting in considerable panic even if you have a fully redundant dedicated server set up.
Email server maintenance- keep your server up to optimum performance standards. Check the server health regularly, get rid of unused applications and tools. Anti spam softwares and anti virus should also be regularly updated.