MarketSharp partners with a company called SendGrid to send e-mails from within our system. The issue of e-mail deliverability arises with SendGrid masquerading as you when sending emails. It is done for the legitimate purpose of making emails sent from within MarketSharp (appointment reminders, follow-ups, thank you’s, etc) to look like they are coming from you. However, masquerading as a trusted source is the same way in which spammers try to trick people into installing malicious software or divulging compromising information. What this means in practice is that a legitimate email is often marked as spam or blocked outright.
The way to correct this is for your domain to mark other sources as legitimate. Sender Policy Framework (originally called Sender Permitted From) enables you to determine who is authorized to send e-mails on your behalf. You can check your existing SPF record at https://mxtoolbox.com/SuperTool.aspx by entering your domain name, clicking the down arrow and selecting SPF Record Lookup, and then clicking the button to do the lookup.
For example, a lot of them will often look like this:
v=spf1 include:spf.protection.outlook.com ~all
To authorize MarketSharp to send email on your behalf through SendGrid you would need to alter it to allow SendGrid's IP addresses to send emails. Sendgrid's IP addresses are: ip4:198.21.7.178 and ip4:50.31.45.105.
After the changes, the SPF record would look like this:
v=spf1 include:spf.protection.outlook.com ip4:198.21.7.178 ip4:50.31.45.105 ~all
Changes can be made with whoever you registered your domain. Once again you can look that up at https://mxtoolbox.com/SuperTool.aspx this time selecting Whois Lookup. You would need to contact your registrar if you need help finding where to edit the SPF record.
After the change has been made, it may take up to 24 hours for the changes to propagate.
For more information:
https://www.gov.uk/government/publications/email-security-standards/sender-policy-framework-spf