When to Reach Postmaster

A postmaster team is the group at a mailbox provider, such as Gmail or Outlook.com, that handles problems with incoming mail. They can lift a block or review a filtering mistake, but only after you’ve done your own homework. This playbook shows you when to contact them, where, and what to write so you get a useful answer.

When to contact a postmaster

Contacting a postmaster is a last step, not a first one. Work through these steps first:

1. Find the cause yourself. Use the provider’s own tools (Google Postmaster Tools, Microsoft SNDS) and a blocklist checker such as MXToolbox. A blocklist is a public list of IPs and domains known for spam.
2. Fix what you can. Repair SPF, DKIM and DMARC. Get off any blocklists. Remove bad addresses from your list. Send a test to the Mailwel test inbox to confirm your authentication now passes.
3. Write down what you did. Postmasters respond far better when you can show your fixes, with dates.
4. Give it time. DNS changes can take a day or two to spread. Reputation takes a week or two to recover.

Also contact them when an error message tells you to, when one provider still blocks you after every blocklist has removed you, or when a provider filters wanted mail by mistake (a false positive).

Where to contact each provider

Gmail

Google has no phone line or email address for sender support.

• Google Postmaster Tools shows your spam rate, authentication and whether you meet Gmail’s sender requirements. Fix anything it flags first.
• Gmail’s sender help pages include a troubleshooting guide and a contact form for bulk senders (people who send 5,000 or more messages a day to Gmail users). Use the form when you meet the requirements and still have delivery problems.
• Google Workspace support is open to you if you send from a paid Workspace account. Your Workspace admin can open a case from the Admin console.

Expect a reply to take days to weeks, if it comes at all. Google handles these requests in bulk. Use the templates below for what to write.

Microsoft

Microsoft has separate forms for its free and paid email services:

• Outlook.com, Hotmail and Live (free accounts): use the Outlook.com sender support form.
• Microsoft 365 (business accounts): use the delist portal to ask for an IP to be removed from its blocked senders list.

Two free programmes give you facts to include, but neither is a support channel:

• SNDS (Smart Network Data Services) shows how Outlook.com rates your sending IPs.
• JMRP (Junk Mail Reporting Program) is a feedback loop: it sends you each email an Outlook.com user reports as junk, so you can remove them. Sign up on the SNDS site.

Always paste the exact error message. Microsoft errors often end with a code in brackets that tells their team which block you hit:

550 5.7.1 Unfortunately, messages from [192.0.2.1] weren't sent.
Please contact your Internet service provider since part of their
network is on our block list (S3140).

550 means a permanent rejection. 192.0.2.1 is your sending IP. S3140 is Microsoft’s code for this block.

Expect an automatic acknowledgement within a few business days. A full answer can take longer.

Yahoo and AOL

Yahoo runs both Yahoo Mail and AOL Mail. Its home for senders is the Yahoo Sender Hub.

• Open a ticket there for delivery problems to Yahoo or AOL mailboxes.
• Sign up there for Yahoo’s Complaint Feedback Loop, which reports every email a Yahoo user marks as spam.

Yahoo expects the exact bounce message, proof that you follow its sender requirements, and proof that the people who complained had signed up. Reply times vary.

Apple iCloud Mail

Apple publishes a postmaster page with its requirements, but offers little direct support. If only iCloud addresses have trouble, check your authentication and make sure you send over TLS (encryption between mail servers).

Writing a request that gets read

What postmasters want to see

Postmaster teams read many requests a day. The ones that get action have five things:

1. Specific facts: exact errors, IPs, domains and dates. “Our email isn’t getting delivered” goes to the bottom of the pile.
2. Proof you investigated: which tools you used and what they showed.
3. Proof you fixed things. For example: “On 1 September we found complaints came from an old list. We removed it. Since 3 September we only email people who opened in the last 30 days.”
4. Proof you’re a good sender: passing authentication, few complaints, subscribers who chose to sign up.
5. A clear, reasonable ask: “Please review the block on IP 192.0.2.1.” Don’t demand an instant fix.

What not to do

• Don’t threaten legal action. Your request moves to the legal team instead of the technical one.
• Don’t just say “this isn’t spam”. Every sender says that. Show evidence instead.
• Don’t use several channels at once. Duplicate requests waste their time and can slow your case.
• Don’t follow up every day. Wait for the stated reply time first.
• Don’t blame the provider. “Your filters are broken” won’t help. “Can you help me understand why my mail is filtered, given these numbers?” will.

Templates

Fill in the parts in square brackets. Delete any line you can’t back up with facts.

Block that stays after you fixed the cause

Subject: Delivery block review request - [shop.example]

Hello,

Mail from [shop.example] / IP [192.0.2.1] to [provider] users is
still blocked.

Error message:
[Paste the exact error]

Timeline:
- Block first seen: [date]
- Cause we found: [short description]
- Fix completed: [date and what we did]
- Block still in place [X] days after the fix

Current data:
- [Provider tool] status: [status]
- SPF, DKIM, DMARC: passing, DMARC policy [none/quarantine/reject]
- Complaint rate: [X%]
- Blocklists: none (checked with MXToolbox on [date])

How we send:
- Subscribers confirm their address before we email them
- Daily volume to [provider]: [number]
- We remove anyone who complains the same day

Could you review the block on [IP/domain] and tell us if anything
else is needed?

Thank you,
[Name]
[Company]
[Contact details]

Wanted mail going to spam (a false positive)

Subject: Spam folder review - [shop.example]

Hello,

Mail from [shop.example] has landed in the spam folder at
[provider] for [X] weeks, even though:

- [Provider tool] shows a spam rate below [X%]
- SPF, DKIM and DMARC pass for all our mail
- We are on no blocklists
- We remove anyone who complains the same day

Seed tests show inbox placement at [other providers] and spam
placement at [this provider].

Could you check whether a specific filter is affecting mail from
[shop.example]?

Example message:
- Sending IP: [IP]
- Message-ID: [message-id]
- Sent at: [date and time, with time zone]

Thank you,
[Name]
[Company]

The Message-ID is a unique label in every email’s headers. You can find it with Mailwel’s header analyzer. It lets the postmaster find the exact message in their logs.

After you send the request

What to expect

• An automatic reply confirming they received it. Keep any ticket number.
• A review that takes from a few days to two weeks, depending on the provider.
• A fix, or a request for more details, such as sample messages.
• Sometimes no reply. If you hear nothing in two weeks, send one polite follow-up.

How to follow up

• Quote your ticket number or original request.
• Say what changed since you wrote, in one short paragraph.
• Wait at least another week before following up again.

If nothing works

• Ask your email platform. Its deliverability team often knows the postmaster teams and can raise your case.
• Ask the community. The mailop mailing list includes people who work at mailbox providers.
• Hire a deliverability consultant. They often have contacts at each provider.
• Look at your own sending again. Sometimes the provider is right, and you haven’t found the cause yet.

Postmaster teams want wanted mail to arrive too. Bring evidence, follow their process, and be patient.

Checklist

• Find the cause with Postmaster Tools, SNDS and a blocklist check.
• Fix authentication, blocklist listings and list quality first.
• Wait one to two weeks and check whether the problem clears.
• Use the right channel: Gmail’s bulk sender form, the Outlook.com form or Microsoft 365 delist portal, or the Yahoo Sender Hub.
• Include exact errors, IPs, domains, dates, your fixes and one clear request.
• Send one request through one channel, and keep the ticket number.
• Follow up once after two weeks if you hear nothing.