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SEMS

How to prevent system emails (SendGrid) from being blocked.

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Hello, 

I am a developer for an app that leverages SendGrid for sending our emails from the system. The app does not send a large quantity of emails but it does send out important emails to users that can cause major issues if the email is not received. SendGrid has a Whitelabel System that I setup by adding CNAME entries. This has helped a bit but I still get complaints about random users not recieving emails and 99% of the time it's due to SpamCop. 

 

I am not able to justify the purchase of a static IP from SendGrid, so I am wondering if there is anything else I can do to alleviate emails from getting blocked. Right now, we are stuck with the default behavior of SendGrid assigning IP addresses dynamically. Our system email DNS is sems.serdp-estcp.org and here are some of the many examples of SpamCop blocking emails...

PM 550 spamcop.mimecast.org Blocked - see http://www.spamcop.net/bl.shtml?167.89.100.251. - https://community.mimecast.com/docs/DOC-1369#550

554 5.7.1 Service unavailable; Client host [167.89.106.170] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?167.89.106.170.

451 Blocked - see http://www.spamcop.net/bl.shtml?167.89.100.251

550 Unable to add '123@email.com' because host 167.89.100.251 is listed on bl.spamcop.net

554 5.7.1 Service unavailable; Client host [167.89.100.251] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?167.89.100.251

550 spamcop.mimecast.org Blocked - see http://www.spamcop.net/bl.shtml?167.89.100.251. - https://community.mimecast.com/docs/DOC-1369#550

554 5.7.1 Service unavailable; Client host [167.89.106.170] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?167.89.106.170. 

 

Does anyone have any experience using SendGrid? Any input would be greatly appreciated.

 

Thanks,

SEMS Team.

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I don't have any direct experience with SendGrid, but suspect that it might not be your fault. The larger the provider, the bigger the chances of innocent victims being adversely affected by the bad behaviour of a small number of other users of their system.

As I type, none of the IP addresses mentioned are currently listed in bl.spamcop.net, One possibility is that they were listed when delivery of the message was attempted and have subsequently been delisted. Another possibility is that the admin of the recipient's server is lazy and has configured their server with a generic message that erroneously mentions Spamcop.

It might be worth some time checking the links mentioned in the NDRs (non-delivery reports). The link provided for genuine listings at Spamcop gives some advice on what to check for. In situations where the IP address isn't actually listed, you might want to use an online tool that checks multiple blacklists. This can sometimes provide clues as to what is happening and why.

 

 

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Thanks for the advice. The issue seems to be that there are a lot of temporary blocks which is leading to problems when important emails generated by the system based on business rules are not received. Unfortunately, many of these emails are time sensitive. 

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Glad that forum members were able to provide useful information. 

I would also suggest that your business/client has made the same assumption that 'most' email users have made based on normal experience with the service.  However, a reading of the email standard will reveal that the standard does not guarantee timely delivery nor delivery of email. 

That does not keep me from being stressed when my copy of the New York Times is not in my inbox when I get up ;-)

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If emails are really important, send them twice by complete separate providers.

 

Say (for lowish volume), Gmail or GMX

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