Filing a Complaint With the Airline: Email, Form or Post?

Three Channels — and the Airline Decides Which One Works

Anyone claiming compensation under EU Regulation 261/2004 first faces an unassuming question: where does the letter go? The regulation itself does not prescribe a form for asserting a claim. In practice, however, airlines set very different rules for where a complaint should land — and anyone who chooses the channel the airline does not process often waits for weeks for a reply that never comes.

For our airline database, we evaluated 50 airlines relevant to Europe (as of August 2026). The picture is clear: 31 of these airlines designate a web form as their complaint channel, 12 an email address, and 7 the postal route. Only 13 of the 50 publish an email address for complaints at all — the large majority therefore deliberately channels passengers into a form. Nine airlines expressly designate their channel as the only one. You can find which channel your airline uses in our airline overview.

“Only via Our Own Form”: What This Means Legally

Some conditions of carriage require claims to be asserted through the airline's own web form. Whether such a clause is valid is decided on a case-by-case basis — but the legal framework sets narrow limits on it.

§ 309 No. 13 BGB (German Civil Code) bars standard terms and conditions from requiring a stricter form than plain text form (Textform) for notices and declarations that a consumer must make to the business, and it prohibits “special access requirements”. And Art. 15(1) of Regulation (EC) No 261/2004 provides that the obligations towards passengers may not be limited or excluded, “in particular by a derogation or restrictive clause in the contract of carriage”. The regulation itself does not prescribe any particular form for asserting a claim.

Clauses of this kind have already failed in court — so far, however, in a different context: the Regional Court of Frankfurt am Main held in 2021, among other things, that a condition was invalid under which passengers first had to submit their claim themselves via the airline's website before they were allowed to assign it to a service provider (LG Frankfurt am Main, judgment of 25 November 2021, case no. 2-03 O 527/19, final). The decisive factor there was that the assignment was being made more difficult, not the form of the complaint — the ruling is therefore not a direct precedent for the complaint channel itself.

As a rule, this means in practice: a complaint sent by email or letter preserves your legal position even when the airline prefers a form. The demand notice that puts the airline in default (§ 286 BGB, German Civil Code) is not tied to any particular form. The dispute-resolution body requires that you have already contacted the airline and given it at least two months to respond — no particular form is required for this initial contact either. And the national enforcement body, in Germany the Luftfahrt-Bundesamt (Federal Aviation Office), expressly lists copies of correspondence exchanged with the airline as documents that can be attached to a complaint. Which building blocks a complete letter should contain is shown in our letter anatomy guide.

Two-Channel Strategy: Protect Your Rights, Get Through in Practice

Legal validity and processing practice are two different things. An informal letter is legally effective — but with an airline whose processing depends on a form, it can still go unanswered. The risk is therefore practical, not legal: it costs time, not your claim.

The pragmatic approach for form-oriented airlines follows from this: do both. Submit your claim through the form as well, so it reaches the airline's system, and keep the dated letter as evidence of when you asserted the claim. Doing both together takes only a few minutes more and covers both sides: formal proof and actual processing.

The reverse holds for airlines with a published complaint email address: the email route is generally the fastest there, because the complete letter with attachments arrives in one piece — a form often forces you to break the same facts down into separate fields.

Proof of Submission: The Step Most People Skip

Regardless of the channel, you should be able to prove that and when you asserted the claim. You will need this proof later with the dispute-resolution body, the enforcement body, or in court proceedings — and it can hardly be reconstructed afterwards.

• Email: Leave the message in the “Sent” folder and attach the letter as a PDF instead of just pasting it into the message body. An automatic acknowledgment of receipt from the airline is the best evidence — keep it.
• Web form: After submitting, take a screenshot of the confirmation page and note the case or reference number. Many forms display it only once.
• Post: Registered mail provides proof of delivery as well; file the certificate of posting together with a copy of the letter.

Which Channel Fits Your Airline?

There is no general recommendation — what matters is what the specific airline designates as its channel. As a rule of thumb from our data: if the airline publishes a complaint email address, that is the most direct channel. If it runs a form, the text should be submitted there, supplemented by your own letter as evidence. If it names only a postal address, the letter should go by registered mail to the department expressly designated for complaints — not to the parent group and not to the tour operator.

Our submission assistant, included in the Plus and Premium plans, handles exactly this branching for you: it recognizes your airline's channel and guides you step by step through submission — with the stored address or the direct form link, ready-to-insert text blocks, and a note on which documents you should have on hand. What each plan includes is shown on the pricing overview.

Checklist: Filing Your Complaint Correctly

• Check the airline's channel: Email, form, or post — and whether the airline designates this channel as the only one.
• Keep the letter complete: Name and booking reference, flight number and date, the delay at the final destination, the amount claimed, and a payment deadline belong in every letter — regardless of the channel.
• For form-based airlines, submit both: The text in the form, and the letter as dated evidence.
• Secure proof of submission: Sent folder, screenshot of the confirmation page, or registered mail receipt.
• Keep an eye on the deadline: How long claims remain enforceable depends on the country — an overview is provided by our page on the limitation periods by country.
• Do not give up after a rejection: We have put together a separate overview of the steps to take after a rejection.

Legal disclaimer: This article is for general information only and does not constitute legal advice. The law may vary in individual cases. For complex situations, we recommend consulting a qualified lawyer or legal adviser.

Frequently Asked Questions (FAQ)

Do I have to use the airline's web form?

Regulation (EC) No 261/2004 prescribes no particular form for asserting a claim, and § 309 No. 13 BGB, the German Civil Code, does not allow standard terms to require a stricter form than text form for declarations made to the user of those terms. A complaint by email or letter therefore preserves your legal position as a rule, even where the airline provides a form. Whether a specific clause is valid is decided case by case.

How many airlines publish a complaints email at all?

In our review of 50 European airlines (as of August 2026), 13 publish an email address for complaints. As their complaints route, 31 name a web form, 12 an email address and 7 the postal route; nine airlines describe their route as the only one they accept.

What is the two-channel strategy?

With airlines that point to a form, submit your case there so it enters their processing queue, and additionally keep the dated letter as evidence of when you raised the claim. That covers both sides: the proof and the actual processing.

How do I prove that I sent the complaint?

For email, the message in your Sent folder together with an automatic acknowledgement of receipt serves as evidence. For a web form, take a screenshot of the confirmation page and note the case reference number. For post, registered mail supplies the proof of delivery. Germany's Luftfahrt-Bundesamt expressly names copies of the correspondence conducted with the company as documents that can be enclosed with a complaint.

Does ClaimEU261 also help with filing the letter?

For a one-time fee of 10.00 EUR, our generator creates an individual complaint letter. In the Plus and Premium tiers, the submission assistant additionally guides you through filing: it identifies your airline's route and shows the stored address or the direct form link along with text blocks to paste.