If you have sent email to a @mailsac.com address or a private domain hosted at Mailsac and it was not received, this document will help you find out why.
Sending to an @mailsac.com Address
If the address you sent to ends in @mailsac.com and the message was not received it could be because of:
The sender has blocked sending to @mailsac.com addresses
Large message size. The max message size is 2.5MB
Throttling by Mailsac. If you are sending a large volume of email, we may throttle the rate of incoming messages
The sending SMTP service has a queue
The sending domain, IP address, or receiving address is on the deny list
The message may have been marked as spam by the Spam Filter.
Sending to a Zero-Setup Private Domain (@mydomain.msdc.co)
The Zero-Setup Private Domains handle all MX record changes. You can start receiving email with virtually no setup. If you are still have problems receiving mail it could be because of:
Sending to a Bring Your Own Domain (BYOD) Private Domain
The BYOD Private Domain requires MX record changes. For assistance in configuring the MX records see our BYODomain Configuration.
Some services place restrictions on the size, type, rate, and quantity of email that can be sent.
GMail is not designed for sending bulk mail. The service places limits on the number of emails sent per day and the number of recipients.
Messages sent through SendGrid are often queued and may not be sent immediately.
Sending from a sendgrid.net address may be impacted by throttling. Many Mailsac customers use SendGrid. Until Sender Authentication is configured within SendGrid, emails will be sent from the sendgrid.net domain. Sending from sendgrid.net email address can cause delays in delivery because of the quantity of mail sent from sendgrid.net to mailsac.com. Email sent to a Private Address or a Custom Domain are throttled at a higher threshold. In order to ensure timely delivery it is recommended to configure sender authentication in SendGrid and use a private address or custom domain at Mailsac.
Whitelisting can be requested for:
IP addresses or networks
Mailsac applies a spam filter to all incoming email.
In the single inbox view, a “spam” label appears in the subject line.
The Unified Inbox displays messages classified as spam in the “Spam” folder. Spam messages skip the inbox.
The spam filter can be controlled at an account level.
Mailsac Deny List
Mailsac does deny email from senders that are impacting the overall stability of our services. Typically, senders are initially throttled. If throttling is not effective senders may be added to the deny list.
Emails from social media and streaming services are blocked. Emails from these services have been used in ways that are against the Terms of Service and Acceptable Use Policy. If you are a QA tester working for a social media company or streaming service and wish to use Mailsac reach out to our support team.
Including the following information will help us identify why you are not receiving mail.
the IP address of your sending server
the email addresses you are sending to, and/or the domain you are sending TO
the from email addresses, and/or the domain you are sending FROM
Time frames when messages were lost. A ball park is ok, like, “from 8am - 9am on Dec 3rd GMT we sent 100 messages and only 85 were received” or just “I tried sending 5 messages from 8am - 9am GMT Dec 3rd and none of them went through”