SMTP Rules

[culthill]

Hello,

We recently came across a situation where a specific company we were trying to send emails to were not receiving them.

While we were debugging we found out the following:

- The company uses a grey list technique when receiving emails, checking to
ensure the smtp server relaying the email is following the SMTP rules.

If the relay server was not following the SMTP rules, all emails from this
server were categoriesed as spam. So would not be accepted.

- It was found that the emails we were sending, were being relayed to
Catalyst2 no problems, but the SMTP relay on mango.catalyst2.com was
breaking a SMTP rule.

- The broken rule was found to be the retry time. The mango SMTP server is
retrying to resend the email too quickly.

I would like to think this was a one off, but to ensure, please could you check the configuration on the SMTP server for mango.

Thank you

[paulredpath]

Hi,

What 'rule' did they say was not being followed on mango? The mail setup on there is the same as our other mailservers which have had no issues with mail sending.

If you can let us know then we can investigate.

[culthill]

Hi,

The company we were trying to send mail to uses "greylisting", as seen at http://www.greylisting.org.

The mango smtp relay server is resending emails too quickly, with mango being categorised as bulk mailing software rather than a ligit smtp relay server, our emails were not getting through.

Thank you

[paulredpath]

Hi,

Mango runs a pretty default install of exim and will retry every 4 hrs for up to 5 days after trying a few times initially, I would suggest that the issue is at their end rather than ours to be honest.

If they are having issues with mango retrying after a few mins (which is standard practive) then they will have issues with a lot of smtp servers.